Gokigenyou, Ikkyoku Ikaga?

At a prestigious girls' school, Sae, a shy high schooler didn't fit in with her classmates. Her daily routine during lunch break consists of playing her Mahjong game on her phone. Due to her hobby being maybe too old-fashioned, she kept it a secret, until she was found out by her class' charismatic rich lady, Chise! Will they with their diametrically different personalities get along through playing Mahjong...?