Tatsuki Arisawa

is a student at the Karakura High School, in the same classroom as Ichigo Kurosaki, her childhood friend and karate partner. When they were children, Tatsuki regularly saved Ichigo when he was getting beaten up, as well as cheering him up when he was upset. A tomboyish karate practitioner with dreams of becoming a vale tudo champion, and already ranking Japan's second strongest in her age group, Tatsuki seems to possess no stereotypically feminine qualities as is typical of female manga characters. Her only obvious feminine trait is how she writes her name: using hiragana: (たつき), though this is because she thinks it looks feminine while she considers the kanji of her name un-cute.

Personality
Personality-wise, Tatsuki is protective and level headed most times, unless someone has done something to her. She uses her great strength to beat up anyone that bugs her. Strangely, she has a lot of insight on Ichigo's personality.

Tatsuki is best friends with Orihime Inoue and is constantly protecting her from men looking for a date, as well as Chizuru Honshō, the school lesbian, who often approaches and grabs Orihime's breasts. Tatsuki has done this since middle school, when she beat up some bullies that were trying to cut Orihime's hair, and had already done so once before her brother died. After that, Tatsuki promised to protect her from anyone who dared to make her cry, and she and Orihime became best friends.

Like many of Ichigo's friends, Tatsuki is spiritually aware to the point that she can clearly see ghosts, hollows, shinigami, and other such supernatural phenomena, though she lacks any unique spiritual powers of her own. She is strong enough to survive spiritual attacks most humans are incapable of dealing with, though this may be due to her karate training. She also has the ability to sense Orihime from almost anywhere, even across dimensions; she is able to sense Orihime when she travels to Soul Society, but remarks that she can't sense her presence after Orihime is taken to Hueco Mundo.

She has shown a very estranged side of her though at some points, mainly showing it to Orihime when their disscussing her affections toward Ichigo. One part, that was cut from the anime, Tatsuki actually was disappointed in Orihime that she didn't take advantage of Ichigo when he thought she was hurt. She then went on to teach Orihime on how to take advantage of Ichigo.

Synopsis
In the earlier parts of the series, Tatsuki mainly hangs out with Orihime, and also protects her from the hollow Numb Chandelier, but gets injured. When Orihime's powers awaken, Tatsuki in turn gets protected by Orihime. Soon after that, Tatsuki begins to see hollows clearly, but never mentions it to Orihime. Tatsuki made Orihime promise that she will come back alive before Orihime goes to Soul Society. Later on, during the first invasion of the Arrancar, Tatsuki nearly dies at the hand of Yammy, who uses his special technique called Gonzui to suck up human souls. A timely rescue by Orihime and Chad saves her. Tatsuki also witnesses the battles between Ichigo, Tōshirō Hitsugaya's team and the arrancar. When Orihime gets taken away to Hueco Mundo, Tatsuki is noticeably upset at her sudden disappearance, punching Ichigo's head through a window and shouting at him for not telling her what he knows. She is later accompanied by Keigo Asano and Mizuiro Kojima to Kisuke Urahara's Shop and sees Ichigo leaving for Hueco Mundo.

Power & Abilities
Tatsuki is considered the second strongest girl in Japan in her age group. She managed to place second in a tournament while she had a broken arm. She seems to have some spiritual power, but so far, she is only capable of seeing spirits (including Shinigami, Hollows, and Arrancar).

Spiritual Power: Her spiritual power is enough to resist from Yammy's Gonzui. In the Karakuriser filler arc it is revealed that her spiritual power manifests itself in flame like blasts which she can shoot out out of her fists or incorporate it in her fighting style easily defeating an average hollow, however since this was shown in a filler arc it cannot be considered canon.

Hand-to-Hand Combatant: As a karate practitioner, she has a level of hand-to-hand skills, enough to defend herself from bad guys.

Supposedly in one of the video games, such as Bleach: Dark Souls, she's supposed to have a few superhuman abilities, such as Shunpo.

Trivia

 * During an interview with Kon (manga only) he teased her for having small breasts (when compared to Orihime) to which she replied they are actually C cup. Her breast size is confirmed in the book Bleach SOULS.