Tatewaki Kuno (九能 帯刀, Kunō Tatewaki?) is a recurring rival of Ranma and could considered be a type of villain as he opposes the main relationship between the protagonists.
Inexplicably, Kuno is in love with Akane Tendo, the fiancee of Ranma Saotome. In the second episode Kuno starts a fight with Ranma after finding he lives with Akane(making Kuno the first rival seen in the show). While their fight is interrupted by Genma, the two would go on to have another later in class.
This battle ended with both Ranma and Tatewaki falling into the pool while grappling with each other. Due to a jusenkyo curse, Ranma ended up changing into his female form. Kuno still grabbing onto Ranma, abruptly found himself holding onto a girl's chest. Girl Ranma quickly shook off Kuno and run off leaving Kuno to wonder about this mysterious girl.
A day later Tatewaki is bothering Akane with his affections when he meets up with girl Ranma again. Kuno says Ranma was a coward for using her to escape their previous bout. This infuriates Ranma who decides to duel Kuno right then and there.
Kuno is now attracted to Ranma's female form, which he calls "Pigtailed Girl," but is too dimwitted to realize 'she' is Ranma. He is also extremely deluded, fabricating absurd reasons for his defeats, thinking he is a samurai and believing himself to be invincible and that every beautiful woman he meets is automatically attracted to him, even when it is obvious that they find him repulsive, Though not as skilled as he would like to believe, it has been noted by Ranma that Kuno could easily defeat Akane if he wanted to, but holds back a great deal due to his affection for her.
His bumbling and stupidity have earned him the nickname "Blue Blunder" among fans, a mockery of his self-given epithet, "Blue Thunder."