Isagi Isahaya

Isahaya is generally kind but reacts badly to jealousy. Losing her place to a younger runner makes her resent Ariake enough to behave in ways that sharply contradict her usual personality.

Once confronted with what she has done, Isahaya is capable of recognizing the ugliness of that behavior. Her insecurity comes from taking athletics seriously and fearing that the work she has invested can be displaced by somebody more naturally successful.

She later becomes protective of Ariake and takes on the attitude of an older teammate rather than a rival, showing that her jealousy does not define their relationship permanently.

Isahaya is a trained sprinter capable of completing 100 metres in twelve seconds flat. She is left-handed and possesses the conditioning expected of a serious Athletics Club member.

Her speed is impressive for a Normal but is still placed in perspective when Medaka pursues her. Medaka can overtake her and land ahead of her, demonstrating the gulf between a trained athlete and an Abnormal of Medaka's level.

Isahaya continues participating in athletic events after her introductory conflict, including broader competitions involving Hakoniwa Academy's clubs.

Isahaya becomes involved in one of the earliest Medaka Box requests when Ariake reports that her running shoes have been damaged and she has received a message telling her to quit the Athletics Club.

Medaka investigates and confronts Isahaya. The resulting chase exposes both Isahaya's jealousy and the reason behind it: Ariake's promotion to a regular position has displaced the older athlete despite Isahaya's years of effort.

Rather than remaining enemies, the two runners reconcile. Isahaya subsequently appears as part of the academy's wider athletic community and becomes a more supportive senior toward Ariake.

Aria Ariake is Isahaya's younger Athletics Club teammate. Isahaya initially becomes jealous when Aria Ariake replaces her as a regular, but later watches over her as an underclassman.

Medaka Kurokami investigates Isahaya's treatment of Ariake and confronts her directly. The encounter forces Isahaya to face the jealousy driving her behavior.

Zenkichi Hitoyoshi assists Medaka in investigating Ariake's request and identifying the conflict within the Athletics Club.

Hansode Shiranui points Medaka and Zenkichi toward Isahaya during their investigation.