Saeki Subaru is a widower who completely dotes on his young son, Sora. He shows himself to be a chivalrous man, who strives to live in a more righteous world. But in reality, he's the right-hand man of a yakuza boss, with a male lover. At Sora's nursery school, he meets the new teacher, Kousei, and they quickly become close. However, Saeki gradually starts to feel that an icy flame is lurking in Kousei's eyes…?