High school student Igarashi Tama has grown accustomed to eating her lunch alone inside a toilet stall, avoiding the eyes of her classmates after being bullied in middle school. One day she discovers that the same cramped stall is already occupied by Tsuda Arisa, a girl who belongs to the top tier of the school social hierarchy. Arisa is not hiding from bullies; she suffers from deipnophobia, a condition that makes it nearly impossible for her to eat in front of others. Rather than avoid each other, the two strike an unspoken arrangement: they will share the toilet space as a secret lunch spot, eating together in private. Tama hopes this arrangement will help Arisa gradually overcome her fear of dining in public while also giving herself a refuge from her own isolation. What begins as a practical compromise slowly deepens into a tentative friendship, as each girl learns about the other's struggles and quietly supports the other through small rituals of shared meals. The story follows their evolving relationship through the school year, exploring themes of social anxiety, trust, and the courage it takes to eat with someone else.