Yuzuru Shiga belongs to the Shiga clan, bound by a childhood arrangement to marry his cousin, Azusa Shiga, securing the clan lineage. His father initially hesitated due to their young age and blood relation when the betrothal was made around their sixth year. During their youth, Yuzuru pledged his fondness for Azusa in a symbolic pinkie promise to stay together, though his commitment seemed less fervent than hers.

Relocating to Tokyo, Yuzuru distanced himself from the childhood pact. He embraced a typical high school life, rising to captain of the archery club. His exceptional skill earned him peer respect and admiration from underclassmen. He also began dating Satomi, a fellow club member.

Azusa's arrival in Tokyo after her mother's mysterious death surprised Yuzuru with her changed appearance, but he remained emotionally detached. He viewed her intense devotion—her claim of avoiding all other boys—as an exaggerated remnant of their past. He openly dismissed the betrothal as irrelevant childhood folly, insisting Azusa would naturally form other relationships. When Satomi expressed concerns about Azusa, Yuzuru interpreted her jealousy as irrational and dismissed it.

As Azusa's behavior escalated into supernatural threats against Satomi, Yuzuru remained largely unaware or skeptical. His trusting nature and view of Azusa as a dependent relative, not a threat, contributed to his obliviousness. Confronted with direct evidence like the murder of Satomi's dog and other paranormal incidents targeting Satomi, he felt conflict but hesitated to blame Azusa.

Recognizing Azusa's murderous intent toward Satomi became Yuzuru's pivotal moment, triggering a protective instinct. He actively intervened to safeguard Satomi. In the climax, he confronted Azusa directly, rejecting her definitively and using his archery skills defensively. Outcomes differ: the manga shows him fatally wounding Azusa with an arrow, holding her as she dies while expressing profound sorrow. The OVA depicts a violent confrontation where he shoots Azusa, prompting her retaliation until Satomi intervenes decisively.

Yuzuru evolved from a carefree adolescent prioritizing normalcy to a resolute protector forced to reconcile familial legacy with present relationships. His ultimate actions severed the clan's arranged ties through lethal means, prioritizing self-determined bonds over inherited obligations.