Matsuyama (松山) is an anthropomorphic cat, and a representative from the National Cat Welfare Federation
In Kiri ni Musebu Yoru, he shows up late to the National Cat Welfare Federation's emergency conference, because of the fact that the Yonesaka Line got delayed. Onodera and the others are thrilled to see him alive, because they thought that he might have been killed along the way just like Torabuchi Misora.
Kiri ni Musebu Yoru (霧にむせぶ夜) - (One-Shot)