Aki Sendou  

, 千堂 亜紀

Harutos half sister left the house where they lived with him and his supposed father after their divorce. she and her mother moved to another place and lived alone for several years until her mother remarried with takahisa, masatos father. on her first day at middle school, along with miharu and masato, she was pulled into satsuki and takahisas hero summoning.