A Shinsengumi investigator (spy). In a group filled with eccentric and reckless personalities, he prides himself on being remarkably "plain" and a "man of common sense." He serves as a vital straight man in the series, a typical hard-worker constantly caught up in the unreasonable rampages of those around him. While highly capable as a spy, he is famous for an episode where he obsessively ate only bean jam buns (anpan) and milk while on stakeout for good luck, eventually suffering a mental breakdown and going on a "sparking" rampage, throwing buns everywhere. He loves anpan and milk. His hobbies are badminton (Minton) and Kabaddi. He is often beaten up by Hijikata for slacking off with Minton, but he remains the unsung hero who supports the organization through steady work.

The Shinsengumi's number two, known as the "Demon Vice-Commander" and feared by the men for his strict enforcement of discipline. He is a heavy smoker, always seen with a cigarette in his mouth. Though he appears cool, proud, and intellectual, he is actually a very awkward, hot-blooded man who deeply cares for his comrades. His most defining trait is being an extreme "mayora" who pours massive amounts of mayonnaise—known as the "Hijikata Special"—onto every dish. Additionally, when a cursed sword manifested his otaku personality, "Tosshi," he transformed into a cowardly bishojo figure collector. He loves mayonnaise. His hobbies are smoking and reading. In his Tosshi state, he enjoys collecting figures, watching anime, and gaming. Despite facing daily assassination attempts from Okita, he continues to be the pillar of the Shinsengumi.

The Captain of the First Division and the Shinsengumi's finest genius swordsman. Contrary to his handsome looks, he is black-hearted, cold-blooded, and the "Prince of the Planet Sadistic." He constantly eyes the position of Vice-Commander and relentlessly harasses Hijikata, often firing a bazooka at him whenever he sees an opening. While he seems lazy, often wearing an eye mask to nap on duty, he is a combat professional with a sharp mind who can calmly assess any situation. Despite his twisted personality, he hides a deep loyalty to the Shinsengumi and Kondo, along with a side that cares for his friends. He loves Tabasco and extremely spicy food. His hobbies include harassing Hijikata, listening to Rakugo, sadistic games, and sleeping whenever and wherever possible.

A skilled swordsman and Captain of the Third Division, serving as the Shinsengumi's internal executioner (the Wolf Tamer). His trademark is his afro hair. He is silent and expressionless, communicating only through a sound like a sleeping breath that looks like the letter "Z," leading others to fear him as a cold, taciturn assassin. In reality, however, he is extremely shy. When he tries to speak to others, he gets so nervous his mind goes blank, and he becomes sleepy and falls asleep—a truly introverted personality. He desperately wants friends, and his internal monologues are actually very eloquent and high-energy. He loves orange juice, sweets, and ramen (perhaps because of the afro?). His hobby is keeping a diary called the "Shimaru Journal," where he meticulously records the names of everyone he meets.

The Commander who leads the Shinsengumi. He is a big-hearted, good-natured, and chivalrous man, earning absolute trust and respect from Hijikata, Okita, and the rest of the men. However, in his private life, he transformed into a dangerous individual who engages in irrational stalking ever since falling in love at first sight with Tae Shimura. Often referred to as a "Gorilla" in the series, he is a "handsome-but-unfortunate" character frequently subjected to gag scenes involving dirty jokes or being completely naked. Nevertheless, when it counts, he is a resolute leader who puts his life on the line to protect his comrades and the city of Edo. His favorite food is bananas. His hobbies are following O-Tae (stalking) and catching rhinoceros beetles. His greatest charms are his positivity that brings smiles to those around him and his overwhelming capacity to never break under hardship.