Yoma is a young Japanese man, of athletic build. He has light hair and a regular haircut, with several unidentified dark strands peeking out of it. Yoma is attractive enough to be scouted as a model. After beginning to train his body, Yoma becomes very muscular, his every muscles developing rapidly and becoming defined. His muscles progressively take the shapes of wings.
After having landed his modeling and acting jobs, Hashimoto starts out as a confident young man with a lot of dedication to improving his body and appearance.
However, his routine of training and fitness slowly grows into an obsession that consumes his life. At first, Hashimoto develops a training regime that he follows strictly, with nothing but protein in his diet and a 7 p.m. sleep schedule. He becomes angry at minor infractions towards his strict training lifestyle and diet. Hashimoto then manages to install a bouldering set all over his girlfriend's apartment building for the sake of training via simple navigation.
Eventually, his obsession with fitness drives him to murder his own girlfriend, his regular deliveryman, and a random stranger that took his personal trainer away from him, as they all disrupted his training regime in some way. After building his body to an amazing extent, Hashimoto's eagerness to further improve it led him to turn his routine treadmill match with Rohan Kishibe at the gym into a life-or-death competition in an effort to make it "fair" for his opponent.
Avatar of Hermes: As the Avatar of Hermes, among other gods of athletes, Yoma Hashimoto is blessed with a supernaturally fit body, which allows him to become very muscled in a short amount of time. Thanks to his muscles, Yoma was shown to be able to perform casual feats such as running backward at 20 kmph or easily throw a 20 kg dumbbell with one hand while running, without breaking a sweat.
Yoma Hashimoto was once scouted by a model production agency because of his good looks. He managed to have photos of him published in a magazine, and had a minor role in a film. During the production, he could see the actors Takeru SatohW and Gō AyanoW from a distance.
One day, his manager told him to work out, as good poses and exuding a certain aura were more important than sheer talent. Thus Yoma began to seriously develop his body by frequenting the Morioh Grand Hotel's gym on the 8th floor. Here, he met Rohan Kishibe, who became his acquaintance as well as a minor rival in a game. Said game was to run alongside each other on treadmills and try to take a small remote first once a certain running speed was reached.
Incidentally, Yoma's progress was remarkable, his trainer and girlfriend Mika remarking how quickly his muscles developed. However, he also developed a narcissistic streak and became obsessed with exercising. Living at Mika's apartment, he soon crowded her home with training equipment, but would also fight with her over his protein-rich diet and general obsession with fitness. Moreover, Yoma scolded a deliveryman who gave him protein for ringing the door bell at 7 p.m., the time at which he wanted to sleep.
One day, Yoma's personal trainer was unavailable because of a client. Frustrated, Yoma stole 270,000 yen from Mika's credit card to subscribe to an expensive training program, covering her apartment and the building's facade with a bouldering set. At wit's end, Mika broke up with him and ordered him to leave. At an undisclosed time, Yoma murdered Mika, the deliveryman, and the other gym client, hiding their bodies encased in cement in various places. His muscles also kept developing at a tremendous speed, eventually taking the shape of wings at the trapezii, ankles, or other areas.
During one of his training sessions, Yoma met Rohan again. Despite a previous loss at their game, Yoma tried to ignore the mangaka until the latter teased him about his career. Upset, Yoma accepted Rohan's challenge. Exhibiting his exceptional body, causing Rohan to lose confidence, Yoma also threw a dumbbell at the window behind them, transforming the game into a life-or-death situation. Still sour about his previous loss, Yoma all but claimed that Rohan cheated and wanted a fair challenge, even breaking three of Rohan's fingers to prevent him from preemptively taking the remote. However, doing so allowed Rohan to partially transform Yoma's arm into a book and rapidly scribble a command.
At the critical moment, Yoma grabbed the remote first. Although he claimed victory, Rohan's command forced him to stop Rohan's treadmill, and Yoma was propelled backward out of the building. Failing to grab the ledge, Yoma only menacingly muttered Rohan's name.
Although his ultimate fate is unknown, Rohan is sure that Yoma's athletic abilities enabled him to survive the fall or maybe stop his fall by clinging to the facade. He also reveals that Yoma is likely an avatar and is currently possessed by the God of Muscle, Hermes. Paranoid that Yoma would come back for him, Rohan decides to run.