Hirose Sumire♀

Sumire is a third-year at Shiraitodai High and president of the mahjong club. She is a friend of Teru and the only person known to Teru who seems to have had prior knowledge of Saki's existence. Like her nickname "Sharpshooter", she is calm and polite to her friends and opponents. She never rushes to make her decision and always calmly thinks about it throughly. Sumire shown worry about Teru Miyanaga's behaviour regarding her little sister, Saki, although Teru never wants to pursue the subject.

Sumire's ability is called "Piercing arrow shots." It allows her to get a direct hit on a player of her choice by changing her hand to target a certain discard. It targets what would be the best offensive play, and can be dodged by making defensive or plain bad play. Unfortunately, the ability can be found out easily: when she's about to use it, Sumire's hand moves a bit and she looks at the player she is aiming at. However, the hand movement is so slight (only moving a few millimetres back) that even her own teammates don't know about it.