Kanji Kokuin is a recurring character in the Power Instinct series, first appearing in the sequel, Power Instinct 2. Kanji is another character in the series who has the ability to transform, but unlike characters who become more powerful versions of themselves, Kanji becomes a weak and short old man (his true base form). In the first couple of games, Kanji's transformations were unique in that he would remain transformed until he performed a move that would switch him between his super form and his weaker form. Since Bonnou no Kaihou, his transformation is normal like Oume's and Otane's and lasts for a limited time.

Kanji is the great grandson of one of the eight brothers from the first Goketsuji generation. He is also a friend of Saizo Hattori's grandfather. Kanji has been a devoted practitioner of martial arts since childhood and becoming the strongest man in Japan was always his goal. During his training, Kanji saved a little girl who was being chased by a wild dog in the mountains. After being saved from the dog the little girl, named Sakurako, she introduced Kanji to her family. There, Kanji met Sakurako's grandfather named Daizo, an expert in the art of Ninjutsu. Eventually, Kanji and Daizo became friends and training partners, improving notoriously his fighting skills. Unfortunately, stories about his adventures and strength where heard by Goketsuji Oshima, an ambitious woman who is convinced that only strong people have the right to belong to the Goketsuji family. Oshima tracked him down and forced him to get married to her young daughter, Oume.

When Kanji met Oume, he thought that maybe everything will be fine... after all, Oume was a beautiful girl. But soon he discovered that she not only had incredible strength, but also an evil personality and was constantly humiliated by her. Kanji couldn't stand this treatment, and soon got himself divorced from Oume a few weeks after their wedding. Because of the rules of the Goketsuji clan, during his marriage with Oume he adopted the Goketsuji surname.