|Image gallery for Tansan|
Tansan is a small white cat who wears a red collar, given by Tōru.
Tansan is tame, and does not play around unnecessarily or does not move around too much. But as stated by Tōru, her cat is sometimes very playful and moves around a lot. Tansan is lovable and likes staying with Tōru, and does not want to leave her side when she gets ready for school.
She was named by Run while she and Tōru were eating at a family restaurant. Run said to name it after her favorite things such as sweets and treats. Run then looked at her mixed soda, stating all the sodas she mixed inside and said "Tansan".