Similar to Akane Tendo, Tatewaki Kuno is madly in love with the female form of Ranma Saotome. However he is unaware that Ranma's female and male forms are the same person and as such refers to Ranma's female form as "the pig-tailed girl" whenever he sees or talks about her. This ignorance has persisted despite numerous events in which Ranma changed from normal to cursed form or vice versa when near Kuno. Nabiki Tendo tried to explain to him that they were the same person, but said that the pigtailed girl's body and soul belong to Ranma, causing Kuno to misinterpret this as her being Ranma's unwilling slave. However following this incident Kuno has not tried to either rescue female Ranma or pursue his male form outside of their normal rivalry.
The relationship began when Ranma challenged Kuno at his first day at Furinkan High School in order to decide who will be Akane's fiancé. During this time Ranma and Kuno both fell into the school pool. Ranma, due to his Jusenkyo curse, turned into his female form but Kuno believed that Ranma had performed some form of trickery and got a girl to replace himself. After being defeated by her, Kuno confessed that he was in love her.
After this Kuno's feelings for "the pig-tailed girl" grew more prevalent, resulting in him having to continually think about who he should be in love with, her or Akane. He has decided that he must have them both and pursues both with equal vigor. This is a very one-sided relationship as Ranma, due to his original gender and generally low opinion of Kuno, has no romantic feelings whatsoever for him. However he has used his female form to his advantage when dealing with Kuno when it comes to getting something out of him or getting him to do something. Despite her continuous leading on of Kuno, this has not dampened his ardour for her. Kuno's persistent obsession has made him one of Nabiki Tendo's regular clients for candid photos of female Ranma, all of which were taken without Ranma's consent and Ranma has not received any compensation from Nabiki for the sale of any of these.