Rikurou Tachibana, a second-year student at South Saintwind Academy, sought cheaper thrills during a Kyoto class trip by visiting the abandoned city of Amidahara while classmates frequented a brothel. Slavers drugged and captured him there. During transport deeper into Amidahara, armed refugees ambushed his group, killing most slaves and slavers. Annerose Vajra intervened, slaughtering the attackers and negotiating with the surviving slaver to acquire Rikurou as payment for sparing his life. She then decapitated the slaver and performed a binding ritual through a kiss, forcibly transforming Rikurou into her immortal thrall. He possesses brown short hair, green eyes, and a pale teenage physique, typically dressed in a white shirt and blue pants. His personality blends pessimism, stinginess, and intellectual curiosity. Though adaptable, he often feels like a "fish out of water" and is described as a "hetare" (cowardly/ineffectual). He serves as the "straight man" in interactions, frustrated by his combat ineffectiveness despite immortality. He harbors lustful feelings towards Annerose and desires to prove his worth to her, leading to rivalry with fellow servant Mitico Fleuretty for Annerose's recognition. As Annerose's immortal thrall, Rikurou cannot die unless she is killed. His body heals rapidly from injuries, though slower than entities like Yatsu Murasaki. He can temporarily remove mental and physical limiters to access heightened reflexes, speed, and strength, causing self-damage offset by his healing. Magically, he possesses a neutral "Opportunist" affinity and can utilize a Familiar Technique linked to Annerose. His primary combat method involves fists. Six months post-transformation, Rikurou works at the Annerose Detective Agency in Amidahara. He handles domestic duties like cooking and cleaning due to Mitico's incompetence, alongside minor tasks such as locating a demon-possessed cat. Missions bring encounters with allies and adversaries like Aishwarya Lai (who reads futures via bodily fluid exchange) and Li Mayfeng of the Nine Dragons syndicate. He assists client Otonashi Miki in finding her missing brother, connecting to attacks by artificial werewolves created by antagonist Barde. Key events include Rikurou protecting Annerose by briefly removing his limiter during a Nine Dragons assault, a lewd encounter with Miki orchestrated by Barde, and participation in Aishwarya Lai's twisted quiz game where Annerose and Li Mayfeng were held captive. After Barde kills Aishwarya and steals a Philosopher's Stone, Rikurou and Annerose seek help from the witch Neu Eazlane. Neu teaches Rikurou a secret technique to confront Barde, who captured Mitico to open an Otherworld Gate using her demonic essence and absorbed souls. In the climax at Barde's base, Rikurou fights solo against Takasumi Chemistries agent Yamada Tarou. Learning Tarou's motives, Rikurou defeats him and convinces him to aid their cause. Tarou directs him to a faster route, where Rikurou rejoins Annerose to stop Barde. They kill Barde and destroy the gate, with Mitico rescuing them during the explosion. Aftermath includes potential relationship outcomes: supplementary material suggests a harem ending with Annerose and Mitico, or responding to new clients like the Taimanin group. An OVA bad ending depicts him searching unsuccessfully for a missing Annerose. His story does not intersect with the Taimanin Asagi Battle Arena (TABA) timeline, where Barde's events are referenced but Rikurou remains unseen during Annerose's interactions. He is similarly absent or uncontracted in the RPGX/Action timelines.