Gokigenyou, Ikkyoku Ikaga?

A high school girl named Sae struggles to fit in at her prestigious private school and spends her lunch breaks playing mahjong alone on a mobile app, believing the hobby is unfashionable. One day, Chisei, the most popular girl in their class, discovers Sae's secret. Despite their contrasting personalities and lack of shared interests, the two begin playing mahjong together.