Shinsaku (しんさくくん) is a hamster that was mentioned in Bonjour, Oshare!. He was Oshare's love interest, and it is implied that they were in a relationship. Not much is known about him as he was only seen in a photo carried by Oshare.
His design is notably very traditional, and he may be inspired by samurai or a different role from feudal Japanese society. Oshare sought out Japanese cultural events so she could learn from them and thus "understand him" better.