Double Baby Mangaダブルベイビー
From Chibi Manga: One day, Mei saw a little boy calling the coolest guy of her class, Ogihara, "to-chan". Does he have already a son?! Plus that boy became attached to Mei, so Ogihara had to ask her to do baby-sitting with him after school! Then, Mei discover that baby-sitting is funnier than she thought. But...what is that strange feeling?!