Nasa Yuzaki's wife. She saved Nasa from getting hit by a truck during a snowy night, and he confessed to her at that moment, taken aback by her beauty. Tsukasa agreed to go out with Nasa on the condition that they get married.
Not much is known about Tsukasa's past. She has a strong love for movies, otaku culture, and of course her husband. Her maiden name is Tsukuyomi (月読).
It's later revealed in the manga that she is the 16 year old daughter of the emperor's subordinate. 1400 years ago, he was ordered by the emperor to burn the potion of immortality given by Kaguya atop Mt. Fuji. Instead, he forced his daughter who was near death to drink the potion. She has since been searching for a way to reach the moon, meet Kaguya, and then hopefully become mortal again.