Kirishima Sasami

Yuki's youngest older sister and twin. She likes to play games and read comics. Often dresses in a cat costume pajamas around the house. She acts childish and playful.

'Brothers and sisters can't get married but they can still make babies together. I read about it in a manga'.

Spoiler

She doesn't want Yuki for herself. She wants to create a harem where all her sisters can be happy with him together. She knows all her sisters are in love with Yuki so it's ok if he forces them a little.