Momotaro Mikoshiba is an energetic underclassman on the Samezuka Academy swimming team, teammates with Nitori Aiichirou and under the leadership of upperclassmen Rin Matsuoka and Sousuke Yamazaki. He possesses distinctive red hair. Momotaro exhibits an enthusiastic and playful personality, often featured in humorous situations and displaying a mischievous streak that contributes comedic moments. His signature "sea otter pose" is a recognizable behavioral trait. His narrative involvement includes participating in a farewell trip with Rin, Sousuke, and Nitori before Rin's departure for Australia, which involved searching for Rin's cat, Steve. While supportive of Rin's ambitions, Momotaro's role centers on his presence within the team dynamic and comedic contributions rather than driving major plot points. Details about his background, family, specific achievements, or character development beyond established relationships and comedic moments remain unspecified.