Ryōga Tosa, alias Pitbull, is a 23-year-old incarcerated for violent crimes committed as a yakuza gunman. Standing 195 cm tall with a muscular build, tan skin, and pale green eyes, his features include short red hair featuring a lighter orange fringe in an undercut style and a small scar beneath his right eye. His distinctive look incorporates multiple piercings: three on his right eyebrow, two studs on his right ear, and four earrings on his left ear, along with tattoos on his left shoulder and right hand. He wears silver rings on all non-thumb fingers and layered necklaces bearing a dog-with-crown pendant. His standard attire consists of a black tank top, camo-patterned pants, a dark brown fur-collared jacket, and red sneakers. His background reveals childhood communication difficulties and violence. Bullied for poor speech starting at age eight, he hospitalized an older child at ten. By 13, he possessed a feared reputation for fighting. At 17, he befriended Satsuki Ito. A pivotal incident occurred at 18; during a conflict coinciding with his mother's declining health, Satsuki took the blame and entered juvenile detention in Ryōga's place. Following his mother's death at 19, Ryōga joined a gang as a "bullet" – a subordinate expected to obey without question. Arrested at 20 for large-scale gang violence, he remains imprisoned at 23, where he co-founds the music unit GokuLuck. Personality-wise, Ryōga struggles with verbal communication, frequently resorting to physical aggression when easily angered. Characterized by the hashtags #FistsOverWords, #MadDogWithSeveredLeash, and #RepayingViolenceBackTwofold, he demonstrates fierce loyalty and protectiveness towards those he considers friends, revealing a compassionate core. Trauma hashtags #MadeAFoolOfDaily, #SacrificedACloseFriend, and #WordsICouldntSay hint at unresolved burdens. His prison routine is rigidly structured: extensive sleep periods and naps intersperse his day, waking at 7 AM after only six hours of sleep. Multiple daily workouts and runs occupy morning and afternoon hours, followed by personal hygiene (showers, baths) and meals within specific time slots. Nighttime activities include smoking, pretending to sleep at lights-out (9 PM), writing lyrics from 10 PM to midnight, and drinking until 6 AM. Within GokuLuck, Ryōga trusts teammates Shion Kaida and Kenta Mikoshiba, whom he calls "Shibaken." Kenta views Ryōga as "a decent class within meatheads," while Ryōga shares "matching interests" with Shion. His relationship with prison guard and unit mate Yuto Inukai is formal, addressed as "Inukai." His most complex bond is with Satsuki Ito, whom he considers an "old friend," though Satsuki labels him a "traitor," referencing their unresolved past. His phantometal, the Savage Grills, are silver grills affixed to his canine teeth, activated by licking them. Additional details note his preferences: favoring meat and beer, disliking shiitake mushrooms, pickled foods, and green peas. On hypothetical days off, he would prioritize working out and writing lyrics. His name etymology combines "endure, surpass" (凌) and "fang" (牙); his surname means "soil/earth" (土) and "help/aid" (佐).