Tatewaki Kuno [1].

Tatewaki is one of the tallest characters and has short, dark brown hair. In the remake, due to digital coloring, her hair was black to match its manga counterpart. Three years ago, her father shaved it during a fight, something she still resents. She normally wears the kendo uniform, known as kendogi, in the form of a white uwagi (also blue in the anime) with a medium-colored hakama (also black in the anime), even at school, rather than the gakuran worn by male students. Once in a competition, she wore bōgu, or training armor. Tatewaki also dressed in a formal male kimono depending on the circumstances. She also wears a purple formal suit during Parent-Teacher Day at her younger sister Kodachi's school.

Tatewaki comes from wealthy samurai backgrounds and speaks in flowery poetic language. No matter how many times Ranma defeats him, he remains extremely confident in his abilities. He has a massive ego, leading Kuno to nickname himself "The Blue Thunder of Furinkan High", a nickname not used by anyone else. He is said to have a deep, passionate obsession with the male Ranma and to be the great-grandson of Master Happosai. He is completely clueless when it comes to Ranma's dual nature, making him the only one in the school explicitly unaware of it even late in the manga (though Principal Kuno and all the teachers except Hinako Ninomiya may be unaware in the anime). He refuses to acknowledge the possibility even when Ranma transforms in front of him, so he may be too caught up in his own delusions to believe it, or simply unable to process the facts of strange phenomena, tales such as a person's physical form changing almost at will. At other times, Tatewaki may be distracted by something (or someone) or simply unconscious when Ranma changes. After Nabiki defined the relationship between the two Ranmas by saying that "the pigtailed girl's body and soul belong to Ranma", Tatewaki interpreted this to mean that Ranma had enslaved the object of his affections, to no surprise from his informant. He spends much of his class time talking to Nabiki, but no real friendship exists between the two, instead simply because they are students in the same class. Nabiki frequently manipulates him for money through deception, information, or the sale of photographs of Little Ranma and her sister.

While it initially seemed as if he was going to "abandon" Akane for Ranma Junior, he encouraged her to maintain her previous enthusiasm, as "she wouldn't allow him to cheat on her sister," and immediately offered her photographs of both of them. Beyond this, she generally seems to view him with disdain, while he has stated that he detests her in return. Her nickname for him, Kuno-chan, is used with extreme sarcasm to underline her dislike. However, she regularly turns to him whenever she needs a quick bit of cash. In the anime, they seem to share a level of friendship partially influenced by mutual gain. The strong rivalry between the Tatewaki and Kodachi siblings is a comical reprise. He once irritated his sister by destroying photographs of Ranma Junior, and she responded by throwing them into the pond of her pet, Midorigame (Mr. Turtle in the Latin dub), and spreading unpleasant rumors about Tatewaki and the pigtailed girl. He also has a little dog named Armadillo, who acts as a taster for any food cooked by his sister. Another common prank is to share everything he writes in his diary with Ranma or any other girl he is interested in, usually Akane. He claims that this helps build trust in a relationship. In the anime, he has been shown allying with either Mousse or Ryoga Hibiki against Ranma, though only by accident in the manga (in Ryoga's case, after seeing a photograph of Ranma kissing Akane, and during a noodle-eating competition, and with Mousse during the Moxibustion Arc). Tatewaki and Ryoga attacked Ranma in "The Grand Plan! Ukyo's Skirts!", as well as trying to stop Ranma and Akane from meeting in "Let's Go to the Mushroom Temple". He and Ryoga tore Ranma apart and sent him to the hospital for a whole month in a full body cast in the first OVA. He also trained with Ranma, Ryoga and Mousse to defeat Ken in "Appear! The One Who Imitates Skillfully".

Even if they can collaborate, Tatewaki is not friends with Ryoga or Mousse and seems to be on slightly better terms with Ranma in the anime, though they generally hate each other more in the manga. Though he mostly acts antagonistic towards Ranma throughout the majority of the series, there have been a few occasions where he has teamed up with, or even asked for help from him in certain situations, either involving arguments with his sister or father. He was willing to provide transport for the other cast members (including Ranma) to Nekonron after Akane was kidnapped by Kirin in the first movie (though it is likely that he was trying to save Akane rather than actually helping Ranma do so).

Tatewaki romantically pursues both Ranma (not knowing her name and that she is actually a boy) and Akane. Despite abundant evidence to the contrary, Tatewaki is convinced that Akane and her pigtailed girl love him despite them having made it very clear that they can't stand him. Despite this, Ranma will sometimes pretend to be interested in him if Tatewaki has something that Ranma needs or wants (a prime example of this being during the Wish-Granting Sword arc). The only girl to willingly pursue Tatewaki romantically during the series is Mariko Konjo, captain of the Seisyun Animation Martial Arts team, but even she quickly lost interest by the end of his introduction story. However, after showing off his immensely powerful Watermelon Slicer move on the beach, he found himself surrounded by mobs of young girls enamored with his ability and his status as an amnesiac, much to Nabiki's disbelief. Tatewaki and Nabiki are a "Fanservice" type couple and without being really true in the anime, mainly in the OVAs (like Ryoga and Ukyo), but it is not at all likely in the manga.

As captain of the Kendo team at Furinkan High School, Tatewaki was the school's most powerful warrior (and the most perverted, according to a classmate) before Ranma's arrival. Initially posing a legitimate threat, he was subsequently used as a running joke and was usually quickly defeated by Ranma. During the "Anime Martial Arts" arc, he remained strictly on the defensive with Akane in Kendo duels. He did not consciously inhibit himself because she was a girl, as she concealed her identity, but also did not use her aerial pressure attacks. He was apparently roughly on par with his sister Kodachi, however after training with Hapossai he became much faster and his movements more precise, giving Ranma a hard time. In both the manga and anime, upon losing his memory during training to cut watermelons, the samurai boy temporarily became much more than a match for Ranma, demonstrating the potential to outwit his nemesis. He has sometimes won fights through the use of magical swords or techniques that gave him the advantage, such as the "wish-granting" sword, with a phoenix located on its head that emits a blinding light, or (anime continuity) Miyamoto Musashi's wooden sword, and Happosai's "elixir of light speed," the whirlwind technique, though in the latter case, it proved to be a placebo-controlled confidence boost. While he has mastered his chosen art of Kendo, he has seemingly managed to learn any unarmed combat skill and is therefore heavily reliant on his Bokken for defense. For this reason, he always carries several of them with him.

Despite his speed, he has never been shown to be relatively strong, though he was able to effortlessly lift at least a three-ton boulder with one hand. Ultimately, Tatewaki's arrogance and delusions may be the main obstacle to his progress as a martial artist.