Ruri Mihashi (三橋 瑠里 Mihashi Ruri) is Ren Mihashi's cousin, Ryu Mihashi's older sister, and Naoe and Reiichi Mihashi's niece. She lives in Gunma, but sometimes comes to visit.
When they were young, Ren and his family visited Ruri and they often played together with Kanou, leading him and Ren to develop a friendship.
During Ren's middle school games, he told Ruri to not attend and thus did not tell her when nor where the games took place, as he was embarrassed and ashamed because of his past failures.
She cheered for Nishiura during their game against Tosei, surprised by how skillfully Ren had played during the game.
Ruri enjoys calling Ren by the nickname "Renren", much to his dismay. Ren's teammates even teased him upon hearing Ruri call him by that nickname.