|Japanese name:||大沼 秋一郎|
|Debut:||Saki (manga), round 56|
|Voiced by:||Eiji Miyashita|
Shuuichirou Oonuma is a professional mahjong player and also does commentary.
Shuuichirou is an old man with balding grey hair and goatee. On his professional mahjong card, he is seen wearing a light brown shirt and a green overshirt, brown pants, and brown loafers, and it is stated that he is 72 years old, 174 cm tall, and weights 68 kg.