Tsukushi is the president of the track and field club. She is also the older sister of Tsukiko. She often bullies Youto, and is the person who made him to be known as Hentai Ouji. She wants to marry her little sister Tsukiko. She is the person who set up the cat statue.
At first she jokingly tries to seduce Youto in an attempt to make her younger sister lose interest in him. However, she also gradually starts to fall in love with him as well, and even believes in his lie, where he suggested that Youto is not Youto, but “Youto’s little brother.” Despite being steel-faced and serious, Tsukushi is actually kinda dumb and wants to move to Massachusetts so she could marry Tsukiko.
It was later revealed in the last episode that Tsukushi’s memories of her mother was given by Youto through the help of the Cat God Statue