Otoha Kuonji is a teenage girl with light blue hair cascading to her hips and striking purple eyes. She is frequently seen in her school uniform, typically adorned with a hair ribbon or bow. As Yukito's childhood friend, she unexpectedly develops romantic feelings for Reiya, creating a complex dynamic where Yukito harbors a crush on her while she is emotionally drawn to Reiya.

Her defining personality trait is profound selflessness. When tragedy strikes the group during their summer house vacation, especially following Kotomi's death, Otoha suppresses her own grief to prioritize supporting others. She focuses intensely on providing emotional comfort, particularly to Reiya, who shoulders blame as the trip's organizer. Actively seeking to alleviate his crushing guilt, she emphasizes the unforeseeable nature of the events.

The group faces multiple perils at the isolated summer house: escaped convicts destroy the main bridge, trapping them; a school doctor blackmails one member using a stolen diary; and internal tensions escalate amidst blurred relationships. Amidst the ensuing chaos and fear, Otoha's actions consistently center on maintaining group cohesion and offering solace to those struggling emotionally.