Reed Lumen is a human boy who regularly takes trips past the barrier to search for humans who have either survived or accidentally found themselves in the Monster Kingdom. He appears to live with his younger sibling Eidolon, and seems to be the son of a prominent inventor or scientist.
Reed has black eyes, dark skin, long brown hair often tied up in a ponytail, as well as a small beauty mark beneath his left eye. His usual attire consists of a sleeveless high-necked zip-up top the color of rust, as well as dark brown pants and shoes. His elbows are normally wrapped in tight bandages where they disappear into his brown mechanical armguards.
- Reed comes from the Old English word reade, meaning "red." It initially began as a nickname for redheaded or rosy-skinned people.
- Lumen comes from the Latin words lux and mensura, and means "measure of light."
- Reed's armguards are shown to display a wide variety of functions, such as being capable of holographic projection, tracking rifts in the Barrier, as well as turning into a wind cannon. However, the mechanisms behind these functions are hardly explained, and even Reed himself doesn't seem to know.
- While not having been stated in the comic itself, various artworks posted by Nights reveal that Reed had lost both of his forearms in what might have been an accident of sorts, and the armguards serve as a mechanical prosthetic.