"Onryou" means "Vengeful Spirit" (kind like "Sadako" from "The Ring").
She is the spirit haunting Senai's apartment; however, despite being a vengeful spirit, she is quite a nice girl who becomes a fan of Saenai's manga. She helps him with the housework and sometimes also with his manga.
She can't speak, but she does write, with a horror film calligraphy.
She befriend Ranko-san, right after meeting her.
Content compiled by AnimeList.moe from publicly available sources.
