A tomboyish karate practitioner with dreams of becoming a vale tudo champion, Tatsuki seems to possess no excessively feminine qualities as is typical of female manga characters. However, she does spell her name using hiragana (たつき), which she thinks looks feminine, because she thinks the kanji of her name looks un-cute.
She is protective of Orihime because men looking for a date—to say nothing of Chizuru Honshō, the school lesbian—often approach Orihime. She is an expert martial artist that places high in Japan's national karate competitions, coming in second in her age group even though she had a broken arm at the time. In addition, she has also tutored Orihime in karate.