|Mamiya Ryouta間宮 良太|
|Hair||Black, Spiky Bangs|
|Body||Pale, Slim, Teen|
|Clothes||Swim Shorts, Vest, Waitstaff Uniform|
|Personality||Kind, Ore, Serious|
|Role||Classmate, Cousin, Full Brother, High School Student, Middle Brother, Part-time Worker, School "Go Home Club" Member, Son, Triplet+ Brother, Tsukkomi, Waitstaff|
|Visual novels||Protagonist - Mamiya-kunchi no Itsutsugo Jijou|
The second youngest sibling of the Mamiya quintuplets. A serious but kind boy with a firm character, he mainly stays in the shadow unlike his sisters. A jack-of-all-trades who also acts as the tsukkomi, often pulling the brakes when things get too crazy or out of hand.