Akihito Akiyama, initially human, grew disillusioned with romance after a painful breakup, prompting him to avoid emotional connections. He found understanding in Seri Kikiyou, a vampire sharing his disillusionment, and they formed a bond. Seri's flirtatious nature eventually sparked romantic feelings in Akihito. Her subsequent withdrawal triggered his mental decline into obsessive fixation, marked by stalking and relentless messaging. This culminated in a confrontation resolved by Kou Yamori's intervention. Following this, Akihito requested Seri transform him into her vampire underling. She agreed, turning him into her offspring. While maintaining a master-servant dynamic, their relationship deepened beyond typical underling connections, earning Akihito the nicknames "Menhera-san" or "Mr. Mental" due to his instability. Physically, Akihito was a tall, thin human with black hair, a mole under his right eye, and thick glasses correcting poor eyesight. Post-transformation, his vision improved drastically, allowing him to discard the glasses. His style shifted from a buttoned white shirt and black pants to darker, looser attire like a dark blue shirt and black jacket, adding two piercings in his left ear. This change projected a more confident, relaxed demeanor others described as "cool." As a vampire, Akihito retained core human traits: kindness, attentiveness, and philosophical insight during clarity. However, he developed an intense thirst for blood, openly expressing urges to bite others, especially those with existing marks like Kou. While gaining confidence, remnants of his obsessive nature surfaced when Seri interacted with other men, driving him to discard reminders of his human past for new memories. His abilities encompassed standard vampiric traits: immortality, levitation, phasing through objects, superhuman speed, strength, durability, and accelerated regeneration. Relationships centered on Seri as his emotional anchor and creator, Kou as a supportive friend, and Kyouko Mejiro as an enemy due to her attempts to harm him and Seri. Akihito's development involved reconciling his human vulnerabilities with his vampiric existence, achieving greater self-assurance while navigating the complexities of his bond with Seri.