Koyo Akiba is a first-string player at the U-17 High School Representatives Selection Camp, officially ranked as the Japanese Representative number 20. He is absent during the early portion of the camp because he is away on an overseas expedition, an assignment reserved for elite prospects. When he finally returns to the facility, his status is immediately challenged. Akiba’s tennis is shaped by his international experience, and he is regarded as a formidable competitor whose skills have been sharpened on a global stage.

His personality surfaces during the brief but decisive match he plays against Kanata Irie, a member of the Genius 10 known for a theatrical, manipulative playing style. Akiba openly dismisses Irie’s flourishes as “cheap theatrics,” revealing a pragmatic or perhaps arrogant mindset that places little value on showmanship. That remark has the opposite of its intended effect: it energizes Irie, who suddenly raises his level and overwhelms Akiba. The loss is swift and costs Akiba his first-stringer badge, demoting him to the second string.

In the larger narrative, Akiba’s role is to illustrate the harsh meritocracy of the camp and the immense gap between even a world-traveled representative and the Genius 10. His relationship with Irie is adversarial and one-sided, as the encounter serves mainly to showcase Irie’s hidden intensity rather than build a lasting rivalry. Akiba’s brief arc does not include a redemption or a second chance on screen, so his development remains minimal after the defeat. His notable ability lies in the polished, aggressive tennis he brought back from overseas competition, though the specific techniques and specialties are not elaborated upon.