Heppokomaru, also known as Gasser in some adaptations, is a fictional character from the anime and manga series Bobobo-bo Bo-bobo. He is a teenage warrior, typically depicted as being sixteen years old and from Puppuu City. His name offers insight into his character, as heppoko translates to untrained or inexperienced, while maru is a common suffix for a samurai or warrior's name. Physically, he is described as having short, spiky white hair with short bangs and gold or red eyes. He is often seen wearing a black shirt featuring a skull and crossbones on the back. His appearance and demeanor are intended to contrast with the series' more flamboyant and nonsensical heroes, as he is generally the quiet and sensible member of the group, serving as a voice of reason alongside the character Beauty.

The backstory of Heppokomaru explains his quest for power and his eventual alliance with the main protagonist. He was formerly an outcast who had been studying a specific power. He was born and raised in Puppuu City, where he trained in his unique martial art to defend his home from the Maruhage Empire, working alongside a senior friend named Fundoshitarou. When the powerful empire general Gunkan attacked and destroyed Puppuu City, Fundoshitarou forced Heppokomaru to flee and seek help. This led him to search for the nosehair-wielding rebel Bobobo-bo Bo-bobo. During his journey, Heppokomaru encountered Beauty, a captive of the empire, and saved her hair, which sparked a deeper interest in her and in Bo-bobo. He officially joined Bo-bobo's team after helping to defeat a block leader and has remained a core member of the group since.

In terms of personality, Heppokomaru acts as a straight man to the absurd antics of his teammates. He is often seen punching Don Patch for being annoying or stupid, reacting with shock when others do foolish things, and maintaining a more grounded perspective on the chaotic situations the group finds itself in. Despite this serious facade, he can sometimes join Bo-bobo in his odd behavior or act strangely on his own. His motivations are deeply tied to a desire to protect Beauty and to earn the respect of Bo-bobo, whom he greatly admires and respectfully calls Mr. Bobobo. Though he is too shy or uncertain to confess his feelings, he harbors a deep love for Beauty, and she cares for him in return, affectionately giving him the nickname He-kun.

Heppokomaru holds several key relationships within the group. He deeply admires Bo-bobo from the sidelines and is one of the few people Bo-bobo will not attack, with the rebel leader acting as a mentor and keeping a watchful eye on him. His relationship with Don Patch is antagonistic; Heppokomaru frequently reacts to Don Patch's stupidity with violence, and Don Patch in turn despises him. In contrast, he gets along well with Tokoro Tennosuke, showing him more concern than most other rebels and collaborating with him in tag-team moves. His most significant personal connection is with Beauty, for whom he has risked his safety on multiple occasions to protect from harm.

The character demonstrates notable development and hidden depths, primarily revolving around the regulation of his power. He wears a collar around his neck that keeps his abilities in check. When this collar is removed, he transforms into an unstable and powerful baby-like persona. In this baby form, his gas powers go out of control, he behaves like an infant, and he has a bad temper, often lashing out at Don Patch. By the time of the Shinsetsu sequel series, he has gained greater mastery over his abilities, making this baby form less common, though it can still surface under extreme duress. In a darker development, Heppokomaru once consumed an evil pill, transforming him into a half-demon with long hair, horns, sharp teeth, and red eyes, wielding a dark version of his fighting style before being defeated and returned to normal.

The most notable and distinctive ability of Heppokomaru is his martial art, the Onara Shinken, which translates to True Fart Fist. In the English adaptation, it is called the Fist of the Back Wind. As the name implies, he uses his flatulence as a weapon. The release of his gas produces a horrid stench that can cause enemies to pass out. He has also shown the ability to shape his flatulence into projectile weapons, primarily orbs, and can use it to propel himself upwards or forwards for increased mobility. By the Shinsetsu series, he is said to have mastered this art, achieving the Awakened Fist of Farts and even acquiring a dark demonic form, showing that his seemingly comedic power can be developed into a genuinely formidable and versatile fighting style.