Sukoya Kokaji is a professional mahjong player and a supporting character of the manga "Saki" and its spin-off manga "Saki: Achiga-hen episode of side-A". She provides commentary alongside Kouko Fukuyo during the East Tokyo prefectural qualifying tournament and the national tournament. She is also a friend of professional player Yasuko Fujita. Although she is a skilled player, Sukoya does not play in many ranked tournaments, thus her world rank remains at number 973. She previously earned a silver medal in a freestyle tournament in Rio de Janeiro and was a member of the national high school tournament champion team ten years prior. She is the youngest person to hold eight titles in mahjong and was seen on the way to winning a record eight titles four years prior to the main story.

Spoiler

During her national high school tournament championship year, Sukoya Kokaji who plays for Tsuchiura Girl's from Ibaraki, defeated Achiga Girls' Academy's Harue Akado in the semifinals. She and Yasuko are among the few who are aware of the strength of Achiga's new mahjong team, which Harue coaches, after viewing its national quarterfinal match.

According to her Pro Mahjong Card, her eights' title is called "Seven Eternal Crowns". She is also formerly world's # 2. She was MVP every year when she played for Ebisu and is currently undefeated in Japan.