Redcaps are a variant of goblins from YGGDRASIL that can be summoned through either using a Horn of the Goblin General under specific conditions or a special book found in Nazarick's library Ashurbanipal.
Redcaps are described as evil and twisted looking goblins. Barring weapon difference aside, every Redcap variant seems to commonly wear a pointed red hat and steel boots.
Redcaps have the ability to hide within their summoner's shadow and possibly their target too for that matter. At the same time, they can even go as far as reemerging out of that person's shadow if ordered to and then carry out their surprise attack.
A Redcap's primary weapon in battle seems to vary among its summoners. For starters, while the ones summoned by Enri wielded long scythes, the ones summoned by Lupusregina were equipped with axes instead.
According to Maruyama, they lack long-ranged attacks, and cannot win in long-distance fights. However, since the Redcaps usually fight together as a unit especially in Enri's Goblin Army with exceptionally high morale, it was impossible to exploit their weakness.
- A Redcap in Scottish folklore is a malevolent, murderous goblin that is said to inhabit ruined castles especially where there were once the scenes of tyranny or wicked deeds and is known for soaking its cap in the blood of its victims.
- Enri has thirteen of these beings as a division called Goblin Bodyguards serving under her leadership in the Goblin Army.
- Lupusregina conjured thirty Redcaps that were estimated to be level 43. She also heavily hinted on the fact that these Redcaps are the lowest-leveled goblins summonable in Nazarick's library.
- According to Maruyama, Enri's Redcaps are around the same level as Lupusregina’s Redcaps.
- Redcap's ability seems to be exactly similar to that of the Shadow Demon's ability.
- Maruyama notes that if a rogue/thief type character left their racial class levels as they are now, it will allow them to become a Redcap. Afterward, not also using the Red Cap classes ability, can result in the character participating in a class event that leads to the acquisition of a special class within the setting. Only one player in YGGDRASIL has ever attained that class after Redcap.
- In the Web Novel, Redcaps are referred as Red Hats (レッドハット).