Tsukasa Hiiragi is one of the four main characters of Lucky Star anime and manga.
Kagami's cheerful and very loopy younger twin sister. She's actually very good at home chores and cooking, although she sometimes has to ask for Kagami's help because she forgets things easily.
In the AWA fics, Tsukasa is a student at the AWA Academy and is part of Class 5.
Tsukasa has an average build, albeit lacking any curves. Like Konata, she is flat-chested and quite small compared to her friends.
She has short, light purple hair accessorized with a yellow headband that has a bow on top; the hair bow often changes position in correspondence to her mood. Her droopy eyes are blue-violet, which seem helpless, nervous and emotional. She obviously has much neater hair than her sister, Kagami.
Her autumn uniform consists of a white long-sleeved blouse that looks extremely loose and makes her look thin and flat-chested. The sleeves of her blouse have dark salmon pink-colored cuffs with two thin, white horizontal stripes going around them, and a dark salmon-pink collar that also has two thin white stripes, with a light salmon pink necktie that is often shown in the anime without a knot, resembling a butterfly. Her skirt is short, reaches her upper thighs, and is the same color as her collar and cuffs. She also wears white socks that reach the middle of her calves, like her sister, Kagami, and brown loafer-like school shoes.
Tsukasa Hiiragi is generally a sweet, naive, innocent and dimwitted person who never gets mad, similar to Miyuki. Her calm, girly, and friendly personality heavily contrasts with that of her sister, Kagami, who is a Tsundere and takes on a much more harsh, tomboyish, and arrogant attitude.
Tsukasa is often overshadowed and compared with her older twin sister, Kagami, because she does not seem to excel at anything, including studying and sports. Because her twin sister is much more capable than her, Tsukasa always needs help from her sister with tasks such as texting, much to the latter's rage.
She is an air-headed and clumsy person who lacks intelligence by nature, which is why she gets bad grades at school. She is also a heavy sleeper, and cannot wake up at a set time, even when someone is present to wake her up.
Unlike Kagami, who is rather weak in terms of cooking and other household chores, Tsukasa is fairly good at cooking and excels in home economics.
- n episode 18, when Konata and her friends play the animal personality game, Konata thinks Tsukasa would be a dog because of her image.
- Tsukasa's favorite color is white.
- She is seen without her bow in Miyakawa-ke no Kufuku.
- Tsukasa shares the creator's pen name, Tsukasa Suina, while her sister shares the creator's actual name, Kagami Yoshimizu.
- Despite having a B blood type, she never gets angry and contrasts the Tsundere personality. In fact, she is so pure that she ranks as a "Good Person.", unlike her sister.
- She is very similar to Ryou from Clannad. Both are very friendly, girly, have short hair, and have mean Tsundere twin sisters with longer hair.
- She is similar to the alternate Yuki Nagato from the Disappearance of Haruhi Suzumiya, as both are dreamy and quiet. Both even have the same English voice actresses.
- Tsukasa is the only character among the four main characters who calls Konata Izumi "Kona-chan".
- Tsukasa is left-handed, like her mean twin sister Kagami.
- Tsukasa is often mistaken for cosplaying as Akari Kamigishi from To Heart when she wears her autumn uniform.
- Tsukasa has the shortest hair out of the four main characters in Lucky Star.