Isamu Tamaru (田丸 勇, Tamaru Isamu) is a supporting character in Kotaro Lives Alone. He is a rather loud neighbor of Kotaro's. He is a divorced father of a boy around the age of Kotaro. His ex-wife refuses him to meet his son even though the boy actually wants to meet his father. He really loves Kotaro, wants to hug him, spend time with him and even gets jealous when Karino spends time with him because Kotaro reminds him of his son.