Айдзава Такеру

Eiko and Chizuru's little brother, who enjoys playing with Ika.

Compared to his sisters, Takeru acts very childish and carefree, and actually goes out of his way to befriend Ika. She appears to regard him mostly with disinterest and appears to have a low opinion of him, though she frequently plays with him anyway. He goes to elementary school and is taught under his teacher, Aiko Saitou. He is friends with a variety of other kids, including Yuuta Matsumoto, Shouta Kuroishi, and Satoshi, among others.