A member of the Devee Tribe which are yellow humanoid creatures that wear pots for hats. Nene poisoned the entire Devee Tribe of Lago Village except for Marumaro and told him that if he retrieved a special elixir from the Ancient Hospital Ruins, that Nene would supply a cure for the Tribe. Marumaro first appears in a Drill Machine on the way to the ruins. When he first encounters Shu, Kluke and Jiro, he is intimidated and fights them. When the ship reaches its destination, Marumaro runs away to find the cure. At the Hospital Ruins, Shu saves Marumaro from the Icefire Wolf Ghost and then helps him find the cure. As they return to Devee Tribe, he gives the tribe the cure and the effects are catastrophic. He soon discovers that Nene tricked him to make himself more powerful and is forced to cure the tribe with a new antidote much more difficult to find and then joins the group afterwards to get revenge on Nene. He has tendency to end his sentences by saying "Maro".

In the anime, Marumaro is obsessed with girls (he also acts like a pervert in the original version, and his actions often end up angering Kluke and Bouquet). He joins up with Shu and Co. after the village he was staying at was destroyed and its inhabitants were captured by twin Shadow users Ivanov and Gustuv. Two years later, Marumaro is back in his village until Noi reawakens his shadow. Upon joining up with Shu and Bouquet, Marumaro develops a competitive rivalry with Noi.

He owns the shadow Saber Tiger who uses monk charged attacks In the anime, Saber Tiger thinks himself of as a defender of justice and encourages Marumaro to feel the same way.