|“||I'm surprised. Those clothes…but, aren't you…?||”|
—Jiruo, to Marulk
Marulk (fan translation: Maruruk) 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 in charge of the telescope inside the camp and is often keeping watch of the surroundings so that a gondola can be lowered when a Delver shows up.
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.
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.
At some point in his past, Marulk was involved in a crash of an airship in the Abyss in which the crew, including his father, lost their life and was later found by Ozen. Following the event, he chose to stay in the Abyss and become Ozen's disciple, but after some time, his eyes developed an extreme sensitivity to the light, so he never returned to the surface.
Seeker Camp Arc
Interested in finding out how two Red Whistle Delvers arrived at the Seeker Camp of their own merit, Ozen instructs Marulk to lend an ear to Riko and Reg in her stead; her reasoning was that it would be easier for children to talk to children. At Ozen's instructions, Marulk gives the two of them Blue Whistles; Ozen notes that it would be troublesome to explain the presence of two Red Whistles in the Seeker Camp, so for the time being they will wear Blue Whistles.
The next morning, following Riko wetting Reg's bed, Ozen walks into Riko explaining to Marulk and Reg what caused her to lose control of her bladder — a strange monster.
Later on, Marulk witnesses, in dismay, Ozen's and Reg's fight. Ozen instructs him to stay put and not to interfere. As the fight continues, one-sidedly in Ozen's favor, Marulk panics more and more, until he decides to disobey Ozen's order and hurries to get the other Subterranean Bandits to stop the fight.
Afterwards, it is reveald that Ozen was trying to provoke Reg and Riko into a fight in order to test if they are ready to make their way further down the Abyss. While she criticizes how Reg and Riko acted in the situation of conflict she praises Marulk, as he was the only one to take the right action in the situation; but also remarks that she will still punish him later for disobeying her instructions to stay put.
After finishing her lecture, Ozen instructs Reg and Riko to stay ten days in the forest behind the Seeker Camp as survival training. Reg and Riko return to the Seeker Camp after ten days and Marulk congratulates them on passing as most people don't even manage to make it even a week.
After the training, Ozen tells Reg and Riko the Abyss causes a person's sense of time to get lost to the point of the possibility time moving far slower in the lower layers. She also shares secrets only known to White Whistle Delvers with them, and gives the Artifact, Blaze Reap, to Riko. Afterwards, Riko and Reg leave the Seeker Camp to advance down to the 3rd layer and Marulk, with the rest of the Subterranean Bandits see them off.
Basic Delving Skills
Marulk has been trained in the basics of delving and displays enough skill and expertise to prove to be a Blue Whistle Delver, despite his young age. As a direct apprentice of a White Whistle, he is considerably more skilled at delving than kids his age and he is capable of surviving on his own in the less hazardous sections of the 2nd layer for at least a couple of days. 
Marulk is in charge of the telescope inside the camp and is often keeping watch of the surroundings so that a gondola can be lowered when a delver shows up.
- His name comes from "Marulk", the Swedish word for "anglerfish."
- Marulk's clothes are order-made, and the head pockets have lenses and other work equipment in them.
|Riko's Party||Riko • Reg • Nanachi • Prushka • Meinya|
|Belchero Orphanage||Belchero • Jiruo • Nat • Shiggy • Kiyui|
|Orth||Hablog • Laffi • Torka • Menae & Sherumi • Mio|
|Seeker Camp||Ozen • Marulk • Simred • Zapo • Yelme|
|Ido Front||Bondrewd • Gueira|
|Ilblu||Wazukyan • Belaf • Juroimoh • Vueko • Moogie • Majikaja • Maaa • Mitty • Poriyon • Mepopohon • Embellith • Shurekaka|
|Abyss||Lyza • Srajo • Wakuna • Irumyuui • Ajapoka• Faputa • Gaburoon • Minor Characters|