Ryukkuman hails from the planet Lilulu (alternatively called Riruru or Liluru), one of 245 inhabitants whose spaceship malfunctioned, leading to a crash landing on Earth. Residing in the resulting Riruru village settlement, he displays a marked preference for solitude and travel, frequently sleeping beneath trees and vanishing from the community for long stretches. This nomadic existence underscores his independent nature, following his own unique rhythm.

Despite his solitary habits, he serves as a source of guidance within the community, especially for younger characters such as Memole and her friends. He dispenses advice casually during encounters in the village or surrounding areas, reflecting a position of respect and perceived wisdom among the inhabitants. His demeanor draws comparison to a gentler version of Snufkin from the Moomins series, emphasizing his kind, non-intrusive character.

His name carries the literal meaning "Backpack man," related to travel or baggage. Official media, including the television series and the OVA "Marielle no Housekibako," consistently depict him in this supporting advisory role, showing no significant deviation in his core traits or background; no substantial character development or alterations to his function are documented. Alternative romanizations like "Leguman," "Luckman," or "Lyukmann" exist but refer to this same character.