Momotarou Mikoshiba, the younger brother of Seijuurou Mikoshiba, debuts as a new character in the second season. Created to succeed his brother's role, he avoids being a simple comedic copy. He shares Seijuurou's cheerful personality and appreciation for female company but exhibits his own distinct, energetic nature. His more slender, youthful physique underscores his relative immaturity compared to others. As a first-year student at Samezuka Academy, Momotarou injects vibrant energy into the swim team. His highly energetic actions and vigorous behavior provide frequent entertainment within the series. Interactions, particularly his crush on Matsuoka Gou, showcase his playful and occasionally flirtatious side. In his swimming persona, his eyes flash a challenging "come and get it" attitude, while his clenched fist visibly pulses with intense desire for victory. Described as sparkling "like a raw ore," this characterization emphasizes his untapped potential and future possibilities, positioning his development as intrinsically linked to growth within the sport. His relationship with his older brother, Seijuurou, forms a significant background element and receives narrative focus later, exploring their familial dynamic and its influence on him. Fan-created content often explores his romantic potential through scenarios like surprise visits, playful teasing, or developing affections, though these remain non-canonical interpretations. Visually, his character design creates a distinct presence, frequently noted for bright orange hair and a facial structure featuring a rounded jawline in both fan descriptions and visual media. A character song titled "MOMO'S BEAT" contributes to his official media representation. Momotarou consistently embodies a lively and somewhat naive spirit, representing youthful exuberance. The narrative frames his journey as one of ongoing growth and exploration of his capabilities, both in swimming and personal maturation, frequently explored through team interactions and familial connections.