Tsukasa's physique is a little smaller than average. She has short, purple hair with a yellow ribbon in it that changes position in correspondence to her mood. She has droopy eyes that are light violet. Like her sister, Tsukasa is left-handed. She can be mistaken for cosplaying as Akari Kamigishi from To Heart when she wears her autumn school uniform, which is pointed out twice in the anime: once, when Konata gave her the actual uniform used in the To Heart anime for her birthday, and the second, when two people stopped her at Akihabara to take her picture, much to her embarrassment.
Unlike some of the other characters in the series, Tsukasa has not shown any particular interests in video games and anime, but she does like the Sgt. Frog series, and seems to be utterly obsessed with her pink mobile phone and using it to text people. While she is not good at studying or sports, she excels in cooking. She is portrayed as the stereotypical friendly, airheaded, good-natured but clumsy person. It is often implied that Tsukasa is unable to follow the gist of complex conversations. Like Konata, Tsukasa will often ask her older sister for help on her homework, but while Tsukasa easily forgets her assignments, Konata is just too lazy or preoccupied with her hobbies to do them herself.It is often pointed out,mostly by Kagami, that Tsukasa and Konata are very much alike.
She uses the term "Birds of a feather" to describe their similar bad habits.
Tsukasa tends to dream a lot and think about things. She always likes a good conversation and is always friendly and will never upset her friends. Once, she left instant yakisoba alone after pouring hot water in it, only to come back later discovering there was no water left to drain. Unlike most of the cast of Lucky Star, Tsukasa is a heavy sleeper, and cannot wake up at a set time, even when someone is present to do so.