Marulk is a Delver that lives in the Seeker Camp on the 2nd layer of the Abyss alongside the legendary White Whistle Delver; Ozen the Immovable. Despite his young age, he is already a Blue Whistle Delver due to being a direct apprentice of a White Whistle Delver. He is a rather shy, but polite, individual who misses having the chance to talk with people of the same age because he manages the Seeker Camp. Though he does fear Ozen at times, he knows her well and trusts her. Marulk is a young boy with short blue hair and a rounded face. His feminine traits and maid attire leads people to mistakenly identify him as a girl, but he's actually a male. While the details are not clear, it is implied Ozen was the one that decided for him to dress like a maid. In his prior life in Jisweku, Marulk wore the so-called "Moon Outfit". These long-established children's clothes are worn in the far western country of Jisweku and are believed to conceal "Children of the Shadows" from the sun. The Moon clothes consist out of a headwear with a veil covering the back of the child, a formal dress with insignias on it, and formal shoes.