Sensei is one of few Karate teachers in the DC Universe. He was given control over the League of Assassins after Doctor Darrk's death by Ra's al Ghul, but rebelled against Ra's. This was also the time in which he was said to have lost his sanity. He has trained only one student to full mastery at least within regular DC history. That student was Ben Turner aka Bronze Tiger. First, Sensei sought to use him for evil, this made Ben feel bad. Eventually, he left Sensei. Sensei was also the man who incidentally ordered the murder of Boston Brand who became Deadman after his death.
The Dead, the Hook and the Sensei
The man that became Hook was once Roy Martin Matson. At one time, Matson was the Sensei's protege but Matson failed at his attempt to assassinate Senator Kane, a former astronaut who had the ambition to become the United States' next president. Matson used a high-powered rifle to take out Kane but Kane's personal bodyguard saw Matson from afar and took the bullet for the senator. Matson was ordered to abort the mission by the Sensei's facilitator William Smith. The Sensei was disappointed that Matson had failed to conceal himself from Kane's security detail but he was willing to give Matson a second chance to redeem himself. As punishment, Matson was order to perform Yubitsume, a Japanese ritual that is meant to atone for one's offense or failure toward another. Matson's focus was on the blade that hanged over his finger while unaware that the Sensei had an axe in his hand. Just as Matson was about to perform the ritual, the Sensei takes one swift stroke and Matson's right hand is severed. Matson screams in agony as the Sensei gives him his next mission. The Sensei tells Matson that he must find and kill a worthy target who possesses prowess and agility. With Matson's handicap, he must now succeed in perfecting his marksmanship or face the consequences.
Matson arrives in Gotham and finds a poster of Boston "Deadman" Brand as the main performance at Hill's Circus. Matson decides to target Boston Brand in order to regain the Sensei's good favor. Matson succeeds in killing Boston while he was in mid air during his trapeze performance. However, Brand's spirit lives on thanks to the intervention of Rama Kushna and begins to hunt down the Hook.
Deadman's first opportunity to find the Hook takes place when his spirit is summoned by Ms. Magruder, a retired medium from Hill's Circus. Magruder has recently opened her home to the Forever People, a band of teenagers from New Genesis. The Forever People were present when Magruder tried to summon the spirit of her fallen carnie comrade. At first, Magruder's powers were working and Deadman started to take shape in an astral form. He was only visible to Magruder's psyche but Marc Moonrider's Mother Box made Deadman visible to everyone when it bunched together his ectoplasmic atoms.
Deadman told everyone his sad story and about the man with the hook for a right hand. After hearing his story, the Forever People were determined to help Boston achieve inner peace by bringing his murderer to justice. Serifan, Moonrider, Vykin, Big Bear and Dreamer designed a robot that could latch onto Deadman's ectoplasm thereby enabling him to control and inhabit a physical form. Serafin designated this robot as the Follower and designed it to look like Deadman in order to drive terror into the man who murdered Boston.
Unfortunately, the Forever People's stay on Earth has aroused the attention of the Scavengers, a team of highly trained thieves who steal the latest tech from all four corners of the globe. The Director of the Scavengers wants the New Genesis technology that the Forever People possess. The Director has had an operative spy on the Forever People and the operative's latest report disturbs the Director. The operative disclosed that he saw someone resembling Boston Brand within the company of the Forever People.
It turns out the Director was once a member of the League of Assassins just like Matson. Anyone who has failed the Sensei on a mission, has had their right hand severed and replaced with a hook as a sign of dishonor toward the League's reputation. The Director started the Scavengers organization in order to appease the Sensei by equipping his assassins with the latest advances in weaponry. The Sensei was pleased by the Director's ingenuity and rewarded him for his continuous efforts in supplying the League. Director also developed an affinity toward other failed assassins who endured the same punishment as he did. The Director along with the other failed assassins created a board of directors who each controlled a certain operation around the globe. Each director raised their hooks with pride and the Scavengers were born.
The Director was well aware that the Sensei had taken Matson under his wing and despite his failure to kill Senator Kane, the Sensei had given Matson a second chance to prove himself worthy within the ranks of the League. Matson turned down the Director's offer to join the Scavengers but the Director still felt a personal responsibility to protect his handicapped comrade from the wrath of Deadman. The Director orders one of his operatives to steal the Follower robot before its completion thereby slowing down the Forever People's efforts and allow the Scavengers to dissect the Follower for any promising tech. The operative was successful in stealing the Follower robot but he failed to anticipate the tracking device that Serafin installed inside the robot.
Deadman and the Forever People track the robot to the Director's Scavenger Depot. Deadman infiltrates the Director's quarters and finally takes possession of the Follower. Once he was inside the robot, Deadman noticed the Director's right hand was actually a hook. Deadman automatically assumed that the Director was his murderer. Deadman charged after him but the Director came prepared. The Director used a replica of Mr. Freeze's freeze gun and froze Deadman's robot body. The Director was disappointed that he had to destroy such a priceless piece of machinery but he was proud none the less when he shattered the robot's frozen body into a million pieces.
Deadman was once again reduced to his spectral form. The Forever People made short work of the Scavenger operatives and managed to apprehend William Smith, the manager of the Scavenger Depot. The Sensei placed Smith within the Scavenger organization in order to make sure the Director wasn't holding out on the League. As Deadman wept over his short period of being physically visible, Dreamer used her illusion casting abilities to terrify the Director to the brink of a nervous breakdown. The Director and Smith were now under the mercy of Deadman. The Director informed Deadman that there are many Scavenger directors who have a hook for a right hand and they would rather die then divulge any information.
Boston was left with a dead end. Forever People wished Deadman the best of luck in finding his killer but they took the liberty of escorting Smith and the Director to the proper authorities. Deadman returned to the realm where Rama Kushna resided in order to seek more guidance. Unfortunately, Smith was able to escape the Forever People's custody and returned to the Sensei's side.
Hook, Line & Sinker
Rama decides to give Deadman one more opportunity to bring the Hook to justice. Rama's guidance leads Deadman to William Smith who was just contracted to kill a mass murderer named Phil Carling. Deadman follows Smith all the way to Hong Kong. Smith takes the beeline to an antique shop filled with relics and curios. Smith greets the shop dealer and opens the suitcase that he brought with him from Gotham. The suitcase was filled with money. Deadman presumes that a third party must have paid Smith to kill Carling but Smith's services belong to someone else who benefits from the blood money.
The shop keep takes the suitcase full of money and gives Smith another suitcase along with a note. Smith reads the note and swallows it in order to dispose of any evidence. Deadman follows Smith who goes behind the antique shop and finds a car. Deadman tags along as Smith drives the car to his next destination which is the Hong Kong Waterfront. As he was driving, Smith opened the suitcase and pulls out a strange looking gun.
Smith searches all the gin mills along the waterfront until he finally found his quarry...the Hook. Hook notices Smith at the other end of the bar and opens fire. Smith was unable to get a clear shot because Vishnu, the Indian mystic who was present at Brand's murder, was in his line of sight. The Hook escapes to the docks where he had a boat waiting for him. Hook's boat was fast but it was no match for Smith's dead on aim. Smith uses his strange gun to shoot the motor of Hook's boat but rather than stopping the boat, the bullet caused the engine to explode.
Smith grabbed his own boat and searched the wreckage of Hook's getaway boat. Smith finds Hook floating on a piece of the boat and still alive. Smith disarms Hook, binds him with rope and places him in the trunk of his car. Deadman was glad that the Hook had survived Smith's attack because he wanted to dish out his own brand of justice. Deadman followed Smith to the mountainous countryside of Hong Kong until they reached a temple. Smith drags Hook out of his car and brings him before a ghastly stone figure who kinda resembles Buddha.
Smith then activates a trap door by pushing a fake stone tile. Smith and Hook are then transported to the caverns beneath the temple. Deadman follows the two assassins but his attention is turned away when he notices an armory full of strange weapons and artillery. Deadman figures that the Scavengers have been working with Smith's employer. All of sudden, Deadman hears jeers and shouting from a room across the way. Deadman finds Hook standing in the middle of a room surrounded by other assassins who have nothing but contempt for him then a cloaked figure enters the room. The figure unveils his cloak and reveals that he is the Sensei. Deadman recognized the Sensei as the shop keep that Smith had met with earlier.
The Sensei expresses his disappointment that the Hook has failed the League three times. The Hook tries to convince the Sensei that he did kill Boston Brand to prove his worth but he couldn't explain how Brand managed to return from the dead. Boston remembers that his brother Cleveland had kept his trapeze act going in order to trick his brother's killer and lure him out into the open again but Boston's mind was more overwhelmed with anger. Boston couldn't that the Hook had murdered him just to prove himself to a League of Assassins.
The Sensei was well aware that Hook made a second attempt to kill the supposedly resurrected Boston Brand but even then he failed to kill Cleveland Brand thanks to Deadman's involvement. The Sensei could no longer tolerate Hook's ongoing line of failure so he decided to end Hook through combat. Boston couldn't let the Sensei kill the Hook so he took possession of Smith's body and tried to defend the Hook. The Sensei felt a presence over Smith so he disarms Smith and immobilizes him. The Sensei then turns his attention to the Hook.
Boston had only one other option and that was to enter the Sensei's body. Unfortunately, the Sensei's body was the current host of Jonah, Rama Kushna's former crusader of Nanda Parbat. As long as Jonah inhabited the Sensei's body, Boston could not enter. The Sensei put an end to the groveling Hook who had taken quite a beating from his former mentor. The Sensei sends a deadly blow to back of the Hook's head. Boston watched as the Hook's body lay on the floor with his back facing Boston. Boston cries out to Rama that "It can't end this way."
The Sensei disposes of Hook's body by activating a trap door that leads to a river that flows beneath the temple. Just like that, Boston watches as his killer's lifeless body flows down the river's current into nothingness. The Sensei then commands his assassins to leave the room. The Sensei sits down and enters a state of meditation. With Jonah's help, the Sensei communicates with Boston. The Sensei tells Boston that he is well aware of what Hook meant to him. The Sensei asks "You have walked among evil men to find your killer but now he has suffered for his crimes. Does this not put things in balance?"
Boston exclaims his gratitude that the Hook's death was met with swift justice and the Sensei smiles by saying "Then you are satisfied?" The Sensei's question angers Boston. Boston says "Satisfied? It should have been me who dealt the final blow not you. What you did is a mockery of justice. A farce. A fraud. There is no balance here." Jonah then speaks by saying "Now, you have learned as I did. Rama's greatest yet cruelest lesson is to live with an eternity of frustration and dissatisfaction."
Resurrection of Ra's Al Ghul
He was responsible for trying to cause an earthquake to kill a number of delegates, but was stopped by Batman. Now he is attempting to take control of the League of Assassins over from the revived Ra's Al Ghul and has been revealed as his father.In this story, Sensei reveals that he is the father of Ra's Al Ghul. Batman (Bruce Wayne) ends up getting fatally wounded by Ra's al Ghul because Ra's is after the Fountain of Life in Nanda Parbat since he can't get Damian to be his youthful host. The Sensei suprises the both of them and fatally stabs Ra's while Bruce made his way to the fountain. The Sensei and Bruce combat each other near the fountain but they end up falling in. The Sensei seemingly dies in the fountain because the fountain could tell that the Sensei's life was impure while the Batman was saved.
The Eye of the Beholder
The Sensei does indeed resurface thanks to the intervention of Peacock who pitied the Sensei for his former life. She had a vile of the Lazarus Pits' essence and poured it down the throat of the Sensei's corpse. Peacock hoped Sensei's new lease on life will lead him to true enlightenment but Peacock underestimated the side effects of the Lazarus Pits. The Sensei kidnaps Peacock's brother Luki because Luki is the rightful bearer of the Beholder Mask. Sensei was trying to find the Mask of The Beholder in order to wield its power. Batman and Peacock get into a fight with the Sensei but things didn't go in their favor. The heroes manage to getaway from the Sensei and I-Ching meets up with them later.
I-Ching explains to Batman the origin of the Beholder Mask and why the Sensei wants it. The first written account about the Beholder Mask was documented in1700 BC during the Shang Dynasty. The first man to wear the mask was driven to the point of insanity. He destroyed villages along the Yellow River until he was stopped by a group of monks from the Yangtze River. The monks hid the mask in their village but the temptation to wear it grew supernaturally within the village as time went by.
In 1929, a monk returns to his village with Dr. Paul Henry, a renowned archeologist/ architect who was studying China's Neolithic Era. They find the monk's entire village was burnt to the ground and in the middle of the village, the monk finds his brother wearing the mask. The entire village was driven insane by the the mask's presence and they killed each other just so one of them could possess it. The monk kills his brother by severing his head from his body but the monk sustained fatal wounds. With his last breath, the monk asks Dr. Henry to hide the mask so that no one can ever use its power again. Dr. Henry agrees to the monk's final request. The historian retrieves the mask then he makes his way through the bamboo forest of the Yangtze River and heads back to Gotham City.
Unfortunately, the dark magic behind the mask began to effect Dr. Henry mentally. The mask was driving Dr. Henry into committing suicide and whispering hellish things into his ears. Dr. Henry could no longer handle the mask's presence so he calls on his fellow colleagues to aid him in hiding the mask. Dr. Henry and his colleagues were part of a clandestine organization of wealthy architects called the Jade Compass Society who were known for keeping secrets hidden. The society hid the mask in a structure within Gotham thanks to the outside assistance of a Mr. Fong and each member swore to never speak of it again.
Luki began to have visions about the Beholder Mask and the destruction it would bring to Gotham. It was for this reason that the Sensei has Luki as his prisoner. Dick leaves I-Ching with Peacock since she has gone into a deep sleep because she telepathically feels her brother's pain as the Sensei inflicts torture on Luki. As for Dick, he finds out that Lucius Fox's father Jasper was one of the society members who helped Dr. Henry hide the mask. It seems Jasper Fox and Dr. Henry Sinnot worked hard to ensure that certain buildings within Gotham were made historical landmarks.
Dick first goes to Dr. Sinnot's residence to get answers but he finds Gotham PD instead. Dr. Sinnot was murdered and the cause of death was contributed by several stab wounds. Bullock informs Dick that Sinnot had made a call to a Mr. Fong of Fong's Antique Shop and Fong's shop was blown to pieces a few minutes after his phone call with Sinnot. Dick was running out of leads. Jasper Fox was killed an automobile accident, Mr. Fong and Dr. Sinnot were stabbed by something broad like a sword.
Meanwhile, I-Ching puts a pencil and paper near Peacock and Peacock draws her latest vision from Luki. I-Ching uses this information and contacts Batman by via Bat Signal. Peacock's illustration depicted an abandoned butcher shop in Chinatown. Unfortunately, the both of them come under attack by the Sensei who has been putting information in Luki in order to set up the heroes. The Sensei eventually figured out Luki's telepathic connection to Peacock so he used it to his advantage. However, the Sensei did manage to extract the exact location of the mask. The Sensei learned that Mr. Fong hid the Beholder in the archives of the Gotham Library.
The Sensei arrives at the library and makes his way to the archives. The Sensei finds a statue of Thomas Wayne, the library's biggest financier and destroys it. The mask was hidden in the base of the statue. The Sensei places the mask on and senses that he is not alone in the archives. Peacock had followed the Sensei by disguising herself as one of his assassins. Unfortunately, the mask gave the Sensei the ability to drain life from any living thing within a certain distance.
As Batman and Peacock lay on the floor in pain, Luki uses his telepathic powers to remove the mask from the Sensei. The Sensei refuses to admit defeat so he destroys the mask with his sword. The mask shattered into two pieces in Luki's hands. The Sensei was pushed out of a window by Dick but he doesn't fall to his death. The Sensei escaped with nothing to show for it.
The Sensei is a master martial artist and cunning leader. He has been able to beat and wound Batman with relative ease, but due to his age he has incredibly poor endurance and grew tired in only a few minutes.
He appears in the Young Justice episode "Inflitrator" as part of The League of Shadows (Assassins). The Sensei is a facilitator for the Light. The Sensei sends his operatives like the Hook, Black Spider and Professor Ojo to capture and assassinate Dr. Serling Roquette who was working on a way to stop a nanomite plague from destroying a nearby city. The Young Justice team defeat the assassins and the Sensei reports his team's failure but the Light consider this failure on the League's part as a learning experience because now they know who they are fighting.
In Nolan's version of Batman, the Sensei carries himself as Ra's al Ghul. After Bruce's rigorous training with the League of Shadows (Assassins), the Sensei deems Bruce ready to take on the League's next crusade. The Sensei tells Bruce that in order to prove his commitment to the League, he must kill a criminal who murdered his neighbor for the neighbor's land. Bruce questions the Sensei why he must lower himself to the criminal's level by subjecting him to same brutality that he visited upon his victim. The Sensei tells Bruce that as a crusader of justice, one must stomp out evil by any means necessary. Bruce refuses the Sensei's self righteous test and decides to bring down the League's temple. Bruce flings the Sensei's branding iron into the temple's rafters where bags of gun powder are stored. Bruce and the Sensei engage in a brief sword fight until the burning debris from the temple's rafters comes crashing down on the Sensei. The Sensei is killed instantly.