Amagi Mao

He just moved to this town with his mother and older sister.
He is his father's son from a previous marriage; his biological mother passed away when he was young.
His current mother is his father's remarriage partner. Having recently lost his father as well, he now lives with his stepmother and his stepmother's daughter, his older sister.
He and his sister are in the same grade, but since the protagonist was born early in the year, they are effectively about a year apart in age.

After losing his father and facing financial hardship, he ended up renting a vacant house belonging to relatives. The story begins around the time he moved and transferred schools.
He starts at the new school with the new semester, but he doesn't have any close friends yet and feels like an outsider in class.

Then he meets Chris, and the story begins...