The world is at peace. While demons were once at war with humans, nowadays adventurers are entertainers. Monsters and adventurers use avatars in dungeons to fight each other and people are rating the strongest and most entertaining parties. Remmé is a member of the fourth-highest ranked party. However, his party members feel like they can't rise higher in the ranks because they don't think Remmé, a black mage who generally specializes in applying Status Effects, is contributing much. Since parties are limited to five members, Remmé's party members suggest to replace him with someone else. Despite the protests of their party leader and Remmé's best friend, Phoenix, Remmé gives in to the pressure and leaves the party.
Now without a job, Remmé tries looking for another party, but no one is interested in a black mage, until a woman approaches him and invites him to an interview. Remmé quickly finds out that he was invited to the impregnable Demon King Castle, the dungeon his former party has recently started to explore which no one has ever conquered. The woman who invited him is one of the dungeon's four demon generals. When Remmé is introduced to the demon queen, Lucy, she realizes that Remmé must have been trained by her grandfather, a former demon king. She then makes Remmé her chief of staff and dubs him Lemegeton, to fend off any heroes who try to invade her dungeon.
Welcome to the Impregnable Demon King Castle (難攻不落の魔王城へようこそ, Nankoufuraku no Maou-jou he Youkoso) is a web and light novel series written by Hozumi Mitaka. The web novel is published on Shousetsuka ni Narou
, while the light novel is published by GA Bunko with illustrations by Yuuhi.
In 2020, it received a manga adaptation by Jeiichi Kaidou in Square Enix's Manga Up!.
This series provides examples of:
- Attempted Rape: Milla once was drugged and almost raped by drunken men in a back alley. Remmé beat the would-be rapists up and saved her.
- Black Magic: Black mages in the setting focus on causing Status Effects, like Temporary Blindness, Damage Increasing Debuffs or immobility. However, most black mages aren't really effective, nor do they look cool for television, so most parties won't take in a black mage and it's considered a loser class. Those who are effective like Remmé would be constantly surveiled if others learned the truth, because in past wars too strong black magic was used by evil people.
- Classical Elements Ensemble: There are four great spirits in the setting, which represent an element each. However, Phoenix, the spirit of fire, and Aerial, the spirit of air, are the only ones who have made a contract with one of those spirits in the present generation.
- Dude, Where's My Respect?:
- Justified. Remmé is kicked out of his party at the start of the story because none of his comrades besides his best friend and party leader, Phoenix, realize that he is essential in their success. Remmé deliberately doesn't disclose how strong he is (as he was trained by a former demon king), while he made Phoenix promise not to tell. However, they are stuck at 4th place in the rankings, which his comrades believe is because all Remmé is doing is standing around and mumbling some words. Revealing Remmé's abilities is not an option because one of them would never be able to keep his mouth shut and put Remmé on permanent surveillance, while Phoenix not revealing it makes it look like Nepotism. Both Remmé and Phoenix acknowledge that Phoenix would have lost all respect if he had kicked out his other comrades in favor of his best friend.
- Averted with Aerial's Rank 1 party. Aerial has a White Mage in his party, who are usually not well-respected either, but Panacea is so powerful that no one questions her capabilities. This is why white mages have a slightly better standing than black mages.
- Elemental Powers: Adventurers with the Hero class contract with an elemental spirit. Phoenix has a contract with a fire spirit for instance.
- Fantastic Racism: Although there are no more wars, demihumans like vampires still suffer from racism.
- Fighting a Shadow: No one is dying in dungeon raids. Both the "monsters" and the "heroes" use avatars. All they will suffer is a monetary loss, as avatars aren't cheap.
- Quitting to Get Married: Double subverted with Aerial's white mage, Panacea. She didn't quit after marrying, but she wants to settle down after giving birth to her third child, which is why Aerial is looking for a replacement.
- Rescue Romance: Milla started to take a liking to Remmé after he rescued her from an Attempted Rape, despite her earlier mocking him. She began paying close attention to Remmé in the raids and realized that he is far stronger than he is shown to be.
- Short Title: Long, Elaborate Subtitle: The full novel title (難攻不落の魔王城へようこそ～デバフは不要と勇者パーティーを追い出された黒魔導士、魔王軍の最高幹部に迎えられる, Welcome to the Impregnable Demon King Castle – The Black Sorcerer Is Offered a Seat as a Member of the Demon King Army's Top Brass After Being Kicked out of the Hero's Party Because They Didn't Need Debuffs) actually fully describes how the story begins. It's still present in the light novel and manga, but the subtitle is much smaller.
- Show Within a Show: Raids on dungeons only serve as entertainment. Parties stream or broadcast an edited version of their raids. The most successful parties are treated like celebrities.
- Sue Donym: Milla's dungeon name is "Carmilla", while Remmé (or Leme) is given the name "Lemegeton".
