Yuki, professionally known by his stage name rather than his full name Yukito Orikasa, composes music and acts as the tsukkomi in the duo Re:vale alongside Momo. Their five-year partnership thrives on a "married couple" comedic dynamic. Behind his cool demeanor lies emotional sensitivity; he struggles to interpret others' feelings yet harbors deep care for friends and juniors. Songwriting channels emotions he cannot voice aloud. His devotion to Momo drives protective actions, including major personal sacrifices.

Originally, Yuki formed Re:vale as indie artists with best friend Banri. After rejecting producer Kujo's offer over artistic differences, they joined another agency. Tragedy struck during a performance when Banri shoved Yuki from a falling stage light's path, sustaining severe injuries. Desperate, Yuki accepted Kujo's renewed proposal: specialized treatment for Banri in exchange for Re:vale's contract. Banri vanished post-recovery, leaving only a note urging Yuki to "sing honestly." This loss nearly ended Yuki's music career until Momo begged for a month to become his temporary partner—a five-year arrangement or until Banri's return. Though their bond solidified, Yuki secretly planned a Re:vale reunion with Banri for their fifth-anniversary concert.

During *Second Beat!*, Momo's unexplained singing voice loss triggers Yuki's anxiety. Suspecting psychological sabotage or drugging by Kujo, Yuki fears history repeating as the concert nears—particularly another incident endangering Momo. He grapples with voicing his reliance on Momo while covertly continuing his search for Banri. A staged prank by Idolish7 and TRIGGER falsely implicates Yamato in Momo's condition, provoking Yuki's raw outburst. This reveals his profound need for Momo and indirectly restores Momo's confidence. Banri is located, reuniting with Yuki for closure and mutual gratitude, though he declines further contact. Yuki deduces Kujo impersonated Zero to disrupt the concert, recognizing parallels in their fixation on the past.

Yuki practices vegetarianism (preference-based, avoiding meat and fish), holds a phobia of sharp objects, and excels at cooking—gelée vegetable soup is his specialty. He dislikes spoilers due to anxiety over unresolved outcomes, prefers indoor leisure or scenic drives, and becomes absentminded when drinking. Morning wake-ups are a severe struggle, requiring manager Rinto Okazaki's calls and Momo physically rousing him; he self-deprecatingly notes this dependence. Quirks include nicknaming colleagues (e.g., "Honey" for Momo) and a history of letting Momo tie his hair with gaudy accessories while intoxicated.