Hatsumi Usuzumi is a third-year student at Eisui Girls' High School in Kagoshima Prefecture and a supporting character in the manga "Saki". She and the other members of Eisui's team are shrine maidens; she belongs to a branch family of the maidens' lineage on the volcanic island Akusekijima, part of the Ryukyu Islands. Hatsumi ended her match segment in the qualifying tournament with a direct against one of her opponents, winning Eisui the prefectural title and a berth in the national tournament without having teammate Kasumi Iwato play the captain's segment. She is often seen with a ceremonial shaman's mask prior to and following her segment. She has been seen breathing flames from her headdress, which is a Boze mask she may use when performing her duties as an Akuseki shrine maiden.

She can be quite stubborn, still believing that she can make a hand while in the north seat after she was repeatedly blocked by Sae Usuzawa and warned by her teammates. She seems to care a lot about Komaki's well being as she doesn't want Komaki to overexert herself. Hatsumi loves to swim.