A story set in a children's home for girls abandoned by their parents.
"None of us expected that our moms would suddenly leave us."
When her mother Ryoka is arrested for a crime, Maki is sent to live in a children's home. Child Guidance Center employee Kano hands Maki over to the scary-looking Mr. Sasaki, who runs "Kogamo House", a children's home with an eerie atmosphere.
At the home, Maki encounters three girls who can no longer live with their parents for various reasons. The girls don't use their real names, but call each other by nicknames. "Piami", who plays the piano well, "Bombi", who comes from a poor family, and "Post", who has a commanding personality and is the leader of the group.
Post knows the reason Maki was sent to the home and taunts her about it, but receives a backlash from Maki. While the others dream of being taken away by nice foster parents and gaining new families, Maki doubts that that will bring them happiness. She alone believes that one day her real mother Ryoka will come back to get her.