Kato is the partner of the Green Hornet. Initially, Kato was portrayed as Japanese until the invasion of China by Japan in 1937. This was then changed to Kato simply being 'Oriental.' He became Britt's friend when he traveled to the Far East and returned to the states with him to be his assistant and sidekick. Kato is Britt's valet by day and his masked driver/side kick at night. Kato is an excellent martial artist as well as a mechanic, building the Green Hornet's crime fighting vehicle - the Black Beauty.
Now Comics featured many stories about Green Hornet and Kato. A whole genealogy and history of Green Hornet and Kato was established. Ikano Kato, Hayashi Kato, and Mishi Kato. They were the sidekicks for four different Green Hornets.
The history of Kato's life as a Superhero goes back the first Green Hornet, Britt Reid save Ikano Kato from drowning in Japan before World War II. Ikano came to America and eventually joined Britt as his sidekick and fought crime in the City.
Ikano's nationality was hidden during the war as well. His records were changed to show his nationality to be from the Philippines instead. After the war and their last case Ikano went back to Japan and help picked up the pieces of his country. He also married Oshura Oshi and had three sons. He also later married a woman named Maria Granier and had one daughter.
As time went on in the 1960's Hayashi Kato became the new sidekick for the Green Hornet. The Green Hornet was new as well. He did however have the same name Britt Reid. This Brit was the the original Brit's nephew.
In the comics published by Dynamite Entertainment, he is portrayed as Japanese whose full name is Hayashi Kato. It was revealed that he is the son of an accomplished Samurai. Although strangely enough, his father is also a master of Ninjutsu. Details on how he learned the ways of the Ninja remains unknown. Nevertheless, he taught Kato everything he knows and thus he grew into an honorable man and a formidable fighter. Interesting fact, Kato fancies himself more of a Ninja than as a Samurai.
When Japan invaded China in 1937, Kato joined the Japanese Imperial Army to serve his country despite his father's disapproval. At the Nanking Massacre, he witnessed the allowed rape and murder of a young girl by his fellow soldiers. Distraught at the sheer inhumanity his people are capable of, he lashed out and killed them all. He then turned last on his commanding officer, claiming that this was the last life he would ever take and also vowing to never use the Katana ever again after seeing the girl killed with it.
Now a traitor to his country, Kato chose to do whatever he could to impede the Japanese war machine and its atrocities. He sabotaged as much as he could before being captured. He was rescued by Britt Reid and after speaking at length with him, Kato became friends with Britt and offered his services as payment for saving his life. Kato saw this as a master worth serving and a way to regain his lost honor.
Now in America, Britt was impressed as Kato easily he dispatched a crew of thugs that tried to mug them in San Francisco and requested him to teach him how to do that. The duo then learns of the death of Britt's father when they reach Chicago. Kato then helped Britt as they prepared to go against Chicago's top crime boss Skids Carusso. With Kato's knowledge on subterfuge they systematically disrupted Carusso's business ventures one by one. Thus the myth of the Green Hornet was born.
Kato was investigating the murder of a Korean grocer (he was posing a Korean to avoid prosecution) when he saw an ominous message written in kanji that means "coward." He decided to investigate if further and found out that the grocer was in fact a Japanese ninja sent on a secret mission in conjunction with German spies on American soil. With the help of James, a vagabond he met along the way, they were able to put a stop to the their plans.
Kato also put a stop on a drug running operation lead by his friends who does a gig in a Jazz club, in which cost him such grief as he was revealed to be a BIG Jazz fan. He was sent by Britt to investigate what seems to be the largest case of war profiteering being held in a place called the Hellfire Club. He went undercover as an oriental prince tagging James as his "valet" for the mission.
After they successfully cleaned up all the crime in Century City, the Green Hornet and Kato hung up their masks for good, but still remained good friends. Kato went back to Japan where he married a younger woman named Sayomi. Together they had a daughter named Mulan. He then became a famous and respected teacher of the martial arts outside of Tokyo. One night he came home to find his wife slain by a man named Hirohito Juuma who had sworn vengeance against Kato and the Black Hornet for the death of his father, the Yakuza boss Oni Juuma.
After Britt's death at the hands of the Black Hornet, Kato went on to show Britt Reid Jr. his fathers secret.
In this series based on the 2011 Green Hornet film, Kato is Chinese and grew up in Shanghai. He was a factory worker at a young age. It was here he learned how to be resourceful and began to invent and create toys and gadgets. Thanks to his engineering prowess he was accepted in the prestigious Shanghai Technical High school. Despite using his inventions he was still beaten by a bully who knows martial arts. This forced him to learn how to fight and with the help of his teacher, Kato invented his own style of fighting thus paving the way of Kato becoming a formidable fighter.
Kato then got entangled in a mob war between two bosses in an illegal street racing circuit. Kato's automotive and driving skills were honed to the finest as he faced the two mob bosses in winner-takes-all race. In the end they trio went to jail. Kato finished serving time and went on to start a pharmacy selling home-made medicines. He was goaded by Drug-lord to work for him but he refused, this insulted the drug-lord to the point of kidnapping a local girl he had a crush on. Kato went to rescue the girl using the very first Gas-gun. After that he came to America with a Snakehead and found his high school crush now working as an actress which got Kato in show business as a stuntman. All that glitter and glamor ended when he realized that his producer is a sleazy opportunist and gave Kato gave him what he deserved.
Kato found work as a mechanic again this time meeting James Reid who offered him proper immigration papers and a better job as his new personal mechanic.
After defeating Chudnofsky, the Green Hornet is now public enemy no. 1. Kato then orchestrated a feud between two rival biker gangs/drug runners. The ruse proved useful as he was able to take them all down. Until the two homeland security agents mistakenly identified one of Britt's reporters as the Green Hornet.
Although possessing no superpowers, Kato has a lifetime of martial arts training behind him, mastering Bushido and Shinobido to the highest degree. Mostly using his bare hands, he can also formidably use any martial arts weapon and is skilled at improvising weapons out of ordinary objects and using his surroundings. His martial arts training also allowed him to be at peak physical condition.
In addition, Kato is a skilled mechanic, resourceful inventor, expert wheelman and a reliable valet. With no superhero name, Kato has been considered to be the "Black Hornet, to the Green Hornet's sting ..." With this there has been confusion of the Green Hornet and Kato's arch nemesis the Black hornet.
The Green Hornet television series began in 1966 and ran for 26 episodes before being cancelled. Kato was played by the famous martial artist Bruce Lee.
The Green Hornet (1940) - Kato is played by Keye Luke
The Green Hornet Strikes Again! (1941) - Keye Luke returned for the role in the sequel
The Green Hornet (2011) - Kato is played by Jay Chou