Boiled is an assassin affiliated with the agency Dondenkai and a graduate of the Japan Clear Creation, the assassin training school. He serves as a significant early antagonist, confronting the retired hitman Taro Sakamoto during a family trip to an amusement park. He is typically seen alongside his combat partner, Obiguro.

Physically, Boiled is a tall man with a short brown beard and a distinctive scar on his left cheek. His characteristic attire includes a pink beanie, a pair of sunglasses, a short-sleeved white shirt printed with hand grenade designs, and jeans with beads attached to the pockets.

The central pillar of Boiled's personality is his obsession with being hard-boiled. To him, this represents the highest state of being a person can achieve, characterized by extreme toughness and a cool, collected demeanor. He strives to embody this ideal at all times, although he is prone to emotional outbursts, particularly when his partner acts in ways he deems inappropriate. Despite his violent profession, he adheres to a personal code of honor, refusing to take any life other than his designated target. This respect for life extends to small creatures, as he once stopped Obiguro from stepping on an ant. He is also a heavy drinker and a frequent smoker, often seen with a cigarette after a battle.

Boiled's motivations are deeply rooted in his past. At the age of fifteen, he met and befriended Taro Sakamoto at the JCC. He admired Sakamoto greatly, viewing him as a kindred spirit. However, their friendship was largely one-sided. Boiled grew resentful as Sakamoto, indifferent to him, gained popularity and initially failed to recognize him. This perceived slight festered over the years, and Boiled vowed to make Sakamoto remember him. When he encounters a retired, out-of-shape Sakamoto, his resentment turns to anger, as he believes his former idol has become weak and lost his hard-boiled edge.

In the story, Boiled is hired to collect the bounty on Sakamoto's head. He orchestrates an ambush at an amusement park where Sakamoto is spending the day with his family. While Obiguro captures Sakamoto's wife and daughter, Boiled engages Sakamoto directly. Their fight is both a physical confrontation and an emotional reckoning, as Boiled unleashes his pent-up frustration. After being defeated, he finally acknowledges that Sakamoto's new way of life—protecting his family—is its own form of being truly hard-boiled. He then vows to never go after him again and even shows deference to Sakamoto's fierce wife, Aoi, recognizing her as incredibly hard-boiled as well.

Key relationships define his character. His partnership with Obiguro is a constant, though he frequently chides her for her lack of manners. His primary relationship is with Taro Sakamoto, a mix of long-held admiration and bitter rivalry that ultimately resolves into respect. He also has a history with the elite assassin Nagumo from their school days.

Boiled is a formidable fighter, possessing enhanced strength, speed, reflexes, and durability. His combat style relies heavily on unique explosive equipment. He wears an Explosive Gauntlet on his left hand, which he can stuff with dynamite to perform the Rocket Dynamite Punch, a devastating blow with explosive propellant. He also employs Super Ball Bombs, small but powerful bouncing bombs that he throws with pinpoint accuracy, allowing him to strike from unexpected angles. While powerful enough to overwhelm many opponents, his strength is noted to be below that of the elite assassins in The Order. Following his defeat at Sakamoto's hands, Boiled is forced to take on illegal jobs and is eventually captured and imprisoned in the Karatsure organization's B1 prison block.