日向 サキ

The protagonist's older sister, currently a university student (age 19). She has a bright and bubbly personality, and often uses her older sister privilege to tease the main character.

She is a bit outspoken, but at her core, she loves her brother and gets along well with him. She loves Mayuri as if she were her own sister.

When her parents divorced when she was young, she and Mayuri continued to take care of Kouta. She got herself a boyfriend when she entered university.