Abe no Yasutsugu serves as one of the Eight Guardians to the White Dragon Priestess, embodying Genbu of Earth. This onmyōji of the Abe clan was magically created by Seimei's son using residual yin energy left after crafting his predecessor, Yasuaki. Insufficient energy delayed his physical manifestation until five years after Seimei's death. His existence follows an unusual cycle: he remains awake for three consecutive months, requiring neither sustenance nor rest, followed by a three-month hibernation. During dormancy, he absorbs environmental energies accelerating his physical maturation. Though his body appears 21 years old, he has existed for 89 years, aging at a rate of one day equivalent to fifteen normal days. As a non-human entity, he initially lacks emotions, physical sensations, and the need for nourishment. He possesses superhuman endurance, strength, and an eidetic memory. His magic sustains his form; severe depletion can render him unconscious or cause him to cease existing entirely. He wields a yang-enhanced gem necklace for spellcasting and employs avian-form shikigami. After leaving the Abe school due to others fearing his ageless nature, he secluded himself at Mount Kita. Before departing, he inherited Yasuaki's diary, which he consults frequently. He occasionally accepts requests from the Abe family delivered via magical paper charms. He encounters the Priestess Karin and becomes her guardian. Skeptical of her authenticity due to parallels with Yasuaki's records, he agrees to observe her and instruct her in elemental manipulation. His self-identity centers on being a useful tool, leading him to express doubt in his capabilities when facing unforeseen challenges like curses affecting the Priestess. His development focuses on his relationship with Karin. Through their interactions, he gradually begins to feel human emotions, culminating in his transformation into a human. This change manifests through physical symptoms like fatigue and chest pain, which he learns signify loneliness. Upon becoming human, he gains the ability to cry and swears to cherish these new sensations. He serves alongside the guardian Motomi, though his blunt demeanor initially hinders their friendship. During shared duties, he demonstrates decisiveness confronting threats like vengeful spirits and political adversaries. His approach contrasts with Motomi's hesitance, particularly when advocating punitive measures against antagonists like Kazuhito. In optional romance routes, he actively pursues understanding human nature, especially the concept of wishing. He seeks to fulfill promises made to Karin and processes emotional milestones like recalling her forgotten comments. His journey concludes with him thanking her for giving his existence purpose and embracing his humanity.