A new transfer student, he replaces Najika as the culinary representative. Seiya bears a striking resemblance to Sora, leading both Najika and Daichi to initially mistake him for Sora. He is quite egotistical, referring to himself as "Ore-sama" instead of the more common "Ore," reflecting his arrogant nature. (In Japanese, different pronouns are used with varying degrees of politeness and formality.)
Seiya openly flirts with Najika in public, causing other girls to envy her. This contrasts with how Sora and Daichi's interactions with Najika evoke jealousy rather than envy. Despite his flirtatious behavior, Najika finds him rather annoying. Over time, he develops feelings for Akane.
He once told Najika that he had given her a flan in the past, leading her to briefly believe that Seiya was her Flan Prince. However, when Najika confronted him and mentioned liking someone else, talking about how this person saved her on a particular day, Seiya had no idea what she was referring to. This revelation made Najika question her assumptions again.
It turns out that Seiya did indeed make the flan, but it was Daichi who gave it to her six years ago in Hokkaido.
