Mahiro Sendo is a central figure whose background and actions drive the narrative. She approaches Haruto Kawai, a university student who abandoned filmmaking after his best friend Yusuke Hina's death, requesting his collaboration to finish Yusuke's unfinished film project. During this encounter, Mahiro reveals her presence at Yusuke's death and claims responsibility for it, creating significant tension with Haruto and other film club members, especially Yusuke's sister Asuka Hina, who openly blames her.

Mahiro's claim stems from her perceived involvement in the accident that caused Yusuke's demise. This belief leads her to distance herself from others, feeling unworthy of companionship due to her guilt. She had a prior acquaintance with Yusuke, though details of their relationship or her life before the incident remain undisclosed.

Her personality includes stubbornness, forgetfulness, and a childlike demeanor. She harbors admiration for Karin, a character from an earlier installment in the franchise. Her narrative path is designated as the "true ending," requiring players to complete other character routes first to fully access her arc. This route incorporates segments told from her perspective, deepening the exploration of her emotional state and motivations.

Mahiro's development centers on confronting her perceived guilt and isolation. The process of working with Haruto and the film club to realize Yusuke’s cinematic vision becomes instrumental in addressing unresolved grief and collective trauma. This collaborative effort facilitates reconciliation, particularly with Asuka, leading Mahiro to reconnect with those she had pushed away. The narrative concludes with her reuniting with the group, signifying acceptance and emotional resolution.