Momose Sunohara, professionally known as Momo, is one half of the idol duo Re:vale alongside his partner Yukito Orikasa (Yuki). His initial dream of becoming a professional soccer player ended with a severe injury before a crucial national tournament, leaving him disillusioned. During this low point, his sister Ruri took him to a Re:vale concert featuring Yuki and original member Banri Ogami. Witnessing their performance of Yuki's song "Mikansei na Bokura" profoundly impacted Momo; the lyrics resonated deeply, offering catharsis and reigniting his hope. He expressed this in a heartfelt letter to the duo, which moved Yuki to tears, forging Momo's significant connection to Re:vale. His frequent concert attendance and soccer background earned him the affectionate nickname "Captain" from Banri and Yuki.

At the "Bloody Eve" Christmas live event, Momo instinctively leapt from the audience to physically subdue three attackers assaulting Banri and Yuki on stage. This act earned him the new nickname "Mad Dog" from the duo, who then requested his contact information and hired him as support staff. This role brought Momo closer to them, particularly Yuki, who showed unusual interest in Momo’s opinions on his music. Tragedy struck when a stage accident severely injured Banri, leading to his disappearance and Re:vale's dissolution. A devastated Yuki entered deep despair, harshly pushing Momo away. Undeterred, Momo visited Yuki daily at precisely 11:00 AM for an extended period, pleading to restart Re:vale as a duo. After persistent rejection, Yuki eventually relented, marking Re:vale's rebirth with Momo as Banri’s successor.

Transitioning into an idol proved challenging for the inexperienced Momo. Yuki’s initial harsh training methods later softened, influenced by Banri’s past advice about kindness. Momo’s athletic background aided his dance progress, but he financed professional vocal and dance lessons through multiple part-time jobs, as Yuki struggled with practical employment. Yuki also faced trauma-induced creative blocks, unable to handle sharp objects or compose music. Momo’s unwavering support gradually alleviated Yuki’s burdens, enabling him to write new music again. The first song Yuki composed post-trauma moved Momo to tears of guilt over perceived inadequacies, prompting Yuki to physically comfort him—a gesture symbolizing their deepening bond. Their hard work led to a successful debut under Okazaki Productions.

Momo’s personality is multifaceted. Publicly and on stage, he embodies a cheerful, mischievous "boke" role within Re:vale’s "married couple" dynamic, frequently teasing juniors and using kaomoji in communications. Despite this playful exterior, he possesses high intelligence, emotional maturity, and keen observational skills, naturally bringing happiness to others. He prioritizes others' well-being, especially Yuki’s and their juniors', often to the point of self-sacrifice. He displays nervousness during solos and once experienced psychosomatic voice loss, triggered by fear of replacement as Re:vale neared its fifth anniversary after overhearing Yuki’s continued search for Banri. Though Yuki reassured him he was his "one and only partner... until the day the world ends," Momo’s deep-seated insecurity temporarily prevented him from singing, highlighting lingering doubts about his place.

During the events of *Third Beat!*, Momo engages in a risky alliance with Ryo Tsukumo, who aims to disrupt the idol industry. Recognizing the threat posed by Ryo and the emerging group ZOOL—known for exploiting vulnerabilities—Momo deliberately feigns camaraderie with Ryo to gather intelligence. This decision contradicts Yuki’s principles against becoming a "puppet" for protection, showcasing Momo’s willingness to endure personal moral compromise and emotional strain to shield Yuki and their juniors. This subterfuge strains their relationship, leading to arguments rooted in mutual deception for protection. Ryo’s manipulative tactics, including unsettling analogies comparing talent management to archaeological excavation of mummies, underscore the peril of Momo’s path.

Beyond his partnership with Yuki, Momo cultivates relationships across the idol community. He nicknames Tsumugi Takanashi "Manekko-chan" and shares a close platonic bond with IDOLiSH7's Mitsuki Izumi, bonding over comedy shows and outings. He practices artistic hobbies like nail art, decorating Mitsuki and Nagi Rokuya’s nails. His stated preference for a life partner emphasizes shared joy and laughter. He is a morning person, enjoys Japanese emo rock for mental clarity, played soccer in high school, once dressed as Santa for Yuki’s Christmas Eve birthday, and accessorized Yuki’s hair with a peach-motif hair tie while inebriated.