Minagami Sakuya

Hobbies: Exchanging mail with her brother
Likes: Sleeping, sweets
Hates: Imposing image

Kousuke's blood-related younger sister.
A black-haired beauty. People think she has an uptight personality since she always shows a stern expression. But according to Kousuke, she is just very awkward and actually a good-natured person who always pokes her nose into his matters and helps him. She thinks of herself as not very interesting, but that changes whenever she has a conversation with her brother. She mainly communicate with Kousuke through mail ever since she started to live in a school dorm.

Like Kousuke, she doesn't remember much of her childhood.

Based on the official website