|Manga Debut||Chapter 1|
|Anime Debut||Episode 1|
|Voice Actor||Atsuko Tanaka (Japanese)
Marcy Bannor (English)
Nyamsus is the cat of Junpei's family. At the beginning of the anime and manga, it seems that she only wishes to make life miserable for Junpei but ultimately, she has appreciation for him.
She is the one who brings him requests of the cats in need of his help. She is well known and most cats around Junpei's neighborhood see her as an older sister figure. She reveals (to herself) that she is very much grateful of Junpei since Junpei gave her a home, going so far as to beg in front of his mother while he is crying and ignoring his allergies.
Junpei's conflicts with Kanako coupled with school causes him to drift apart from, according to him, someone very dear to him (Nyamsus). Nyamsus greatly cares for Junpei but shows this subtly like when she claims ownership of the living room so as to prevent Junpei from sleeping in it and catching a cold.