Marukubi Boon, commonly known as Boon Marukubi throughout Osamu Tezuka's works, possesses a thick bull neck, prominent black eyebrows, and large eyes underscored by dark semicircles, modeled after French actor Lino Ventura.

Debuting in the 1952-1968 *Astro Boy* series, Marukubi subsequently appeared in nearly every major Tezuka production, including 14 distinct roles within the *Black Jack* series (1973-1983). He consistently appears as a secondary antagonist, typically a thug or gangster supporting primary villains. His characterization emphasizes physical aggression over intelligence, frequently resulting in manipulation by more cunning allies such as Skunk Kusai, Acetylene Lamp, or Hamegg. This recurring role explores themes of human fallibility and moral ambiguity.

In *Undersea Super Train: Marine Express*, Marukubi acts as a cohort to the criminal Skunk Kusai. He boards the titular train to facilitate a weapon-smuggling operation by concealing disintegrator guns inside dummy passengers used for the test run. During the journey, he participates in Skunk's violent hijacking attempt, confronting protagonists like Shunsaku Ban and Rock. Marukubi dies in the ensuing conflict, one of multiple character fatalities driving the film's narrative.

His broader narrative arc across Tezuka's works frames him as a tragic figure—a "ham-fisted human" compelled to confront humanity's darker aspects through his criminal associations and violent tendencies.