Kazuma Kuwabara is mostly just called Kuwabara. Only his sister Shizuru, and Yukina, who he loves, call him Kazuma. Kuwabara is the second best fighter in Sarayashiki Junior High School with his rival and friend, Yusuke coming in first. He has a gang which he leads. It has him, Komada, Okubo, and Kirishima.

Spirit Detective Saga

In the beginning, Kuwabara is one of the people that appear at his wake when he dies. He is angry and upset that he and Yusuke won't be able to finish their fights. Later on Yusuke posseses Kuwabara's body so he can talk to Keiko who is a classmate, so she can help his body so he can come back to life.

Awhile after Kuwabara goes to the home of Master Genkai, an old woman that is one of the greatest fighters ever. He goes their to ask her about his spirit awareness, but he accidentaly enters himself into her tournament for who will become her successor. He wins the first three rounds easily. During his fight with a guy named Musashi he discovers the ability to use the spirit sword by involuntarily using Musashi's broken sword. His winning streak comes to an end when a guy named Rando fights him. Rando shrinks Kuwabara and nearly crushes him to death.