Atte Taberu to Kakimashite.

Two high school girls, one an introvert and the other with a phobia of eating together, are on their lunch break!

Igarashi Tama, a gloomy high school girl, has a daily routine of eating lunch alone in the toilet at school. One day, Tama witnesses Tsuda Arisa, who is at the top of the school caste system, eating in the toilet and learns that Arisa has a social phobia. In order to help Arisa overcome her social phobia and to eliminate her own habit of eating alone, she begins a secret lunch break!!

(Source: Shogakukan, translated)