An unnamed male protagonist falls alseep at his computer playing a Massively Multiplayer Online Role-Playing Game, only to find himself in the body of his avatar, "Arc", equipped with its strongest armor and weapon from the game. Unfortunately, Arc's appearance was also changed to that of a special skin the protagonist bought: a full-body skeleton. Deciding to become Arc in this new setting, the protagonist sets off hoping to not draw attention to himself, helping others as he can, while finding if there's a way to undo his mistake of looking like a skeleton beneath his armor.
Skeleton Knight in Another World contains examples of:
- Adaptational Villainy: The manga shows an antagonist feeding two people, one of whom he was just groping a moment before, to some monsters he trains for The Empire, while the light novel doesn't.
- Attempted Rape: The bandits that attack Rita and Lauren in the beginning of the story try to rape them, but fortunately Arc shows up in time to intervene.
- Beware the Nice Ones: Arc finds this out when his companion's mother has a practice match with him. She's a much more capable fighter than she initially appears to be.
- Cursed With Awesome: Being a skeleton works for intimidation, but not for anything else, as Arc finds out.
- Dem Bones: Arc is basically a walking talking skeleton.
- Enslaved Elves: Humans will try to capture elves to sell as slaves. Females are usually sold as sex slaves to nobles, while the males are forced to impregnate noblewomen to produce children capable of magic.
- Fantastic Racism: Discrimination against elves and mountain people is actively encouraged by the Hilk religion. This was done because they could instinctively sense that the Hilk cardinals were undead no matter what disguise they took, but this is gradually being undone after they and the pontiff are defeated.
- Huge Guy, Tiny Girl: Arc is definitely bigger than his dark elf companion, Ariane, but there's nothing tiny about her.
- The Necrocracy: It's eventually revealed that the pontiff, who rules the Holy Hilk Kingdom, as well as his seven cardinals are undead.
- Non-Human Sidekick: Arc has one after healing an injury it had; said critter turns out to be a rare spirit animal.
- Rewarded as a Traitor Deserves: During the ambush that takes place at the beginning of the story, the bandit leader kills the guard that betrayed Lauren.