Story
Being a "good neighbor" is just not enough anymore! After school, the third-year high school student Mitsuki's daily routine is to play with the neighborhood kids. As he was playing as usual, a scary-looking man with a scar on his face approached him! He said he wanted to know how to interact with small children for his new brother who will be a new family member due to his mother's remarriage. The scary-looking man turns out to be Kyohei, who lives nearby and is one year younger than Mitsuki.
Synopsis via AniList (English).