Kumiko Agemaki
Kumiko is Kei's little sister. She is lovely, energetic and loves her Big Brother Kei.
It has been revealed in Episode 7 that she has strong attachment to spirits and can clearly see those which are invisible to ordinary people. She pets a cat-spirit namely Itsue which only she can see in the entire household. She saw right through Zakuro at her first meet and addresses her as Mysterious Young Lady.