Hidden Dungeons that no one knows how to enter. Legendary places full of extremely rare magical beasts, magic tools for power beyond measure and items that would be considered a rarity all over the world.To such a dungeon the entrance was opened.
Without telling anyone about this place Ill secretly become the strongest.
This world is harsh to nobles of poverty.Without authority or honor, if I could at least acquire power――
Associated NamesOre dake Irerukakushi DungeonThe Hidden Dungeon Only I Can Enter ~Secretly Becoming World Strongest~俺だけ入れる隠しダンジョン 〜こっそり鍛えて世界最強〜
Also comes with a new manga adaptation. An anime adaptation has been confirmed and will air on the 2021 Winter Season.
- Adaptational Modesty: In the manga, Olivia wears a simple dress. In the original light-novel, she's completely naked since her clothes rotted away long, long ago.
- And I Must Scream: Olivia has been chained inside a dungeon, where no one can see or hear her, for two centuries, and any attempts to free her would kill her. She's ecstatic when Noir chances upon her, and treats her kindly, rather than try to exploit her in any way.
- Aristocrats Are Evil: With the exception of the main characters, and their immediate families, the aristocrats are all entitled twits who preen around based entirely on the merits of previous members of their bloodlines, or use money to skate past any test they can. Noir even lost his job as a librarian in chapter 1 to some unnnamed higher tier noble, who bribed the interviewer, just to deny him the position. In later chapters, this starts to fade as Noir racks up heroic accomplishments, and the nobles realize it's a good idea to be on good terms with a powerful and promising adventurer, regardless of social status.
- Battle Harem: Noir's harem predominantly also accompanies him on quests for the adventurer's guild and can hold their own in a fight, thank you very much.
- Blessed with Suck: Olivia is somehow able to live over a century without need for food, water, or having to worry about her "ahem" biological functions, but she's chained to the wall of a dungeon, unable to leave without dying. Noir starts the story only with a "Sage" ability that allows him knowledge beyond any mortal, even using it to find the titular Hidden Dungeon, but the drawback is a massive, crippling migraine that won't go away until Emma comes along and kisses him on the lips.
- Big Brother Attraction: Though Noir completely deludes himself otherwise, his younger sister Alice is very interested in a relationship with him that involves erotic acts.
- Cast from Lifespan: How curse-breaking magic works. Luna, and her mother, were born with the ability, and to break curses, they have to sacrifice a portion of their life-span, the stronger the curse, the greater the cost.
- It's implied that Luna has already significantly shortened her lifespan through this before Noir changed her ability. Though being a half-elf she can still expect to live for a long time.
- Cast from Money: Both Noir and Luna eventually get their special abilities to work this way, should they wish. Noir changes Luna's curse-breaking cost from lifespan to money so she can break curses without it killing her, and Noir crafts a skill to allow him to acquire LP for gold, though he prefers to get LP from the loving of his Rescue Romance harem.
- Casual Kink: Noir has gained LP from being on the "M" side of some S&M play on several occasions, namely being sat and stepped on.
- Childhood Friend Romance: Noir and Emma have been friends since childhood, and they see nothing wrong with kissing each other on the lips, or doing other "couples only" things.
- Fair Weather Friend: On several occasions, Noir gets the cold shoulder from some higher-ranked noble because his family is both "upstart fake nobles," the Baronet, and poor. When some even higher ranked noble comes along and gets friendly with Noir, suddenly the dismissive noble decides to show Noir decency. Noir doesn't play along.
- Harem-Powered: Noir's special ability requires LP, which is gained from, among other things, engaging in erotic acts with members of the opposite sex. There is a very quick "rate of diminishing returns" when playing around with the same girl over and over again, as such, Noir, and Olivia, the one who granted him this power, need a harem to make the most of it. Emma is resigned to it, but does not like it.
- Killer Rabbit: Parodied. One of the first monsters Noir and Emma are sent to hunt down is a rabbit, but what makes it dangerous is that it has the size, strength, and temperament of a bear, without losing any of a rabbit's speed or agility. What's worse is that said rabbit also has a horn on its head to make its charges even more lethal.
- Mate or Die: Though it hasn't gotten that far, yet, if Noir's LP ever reaches 0, he's dead, so he must engage in erotic acts with all the girls of his harem, and a few outside it, just to stay alive.
- No Antagonist: The conflict in the story is Noir vs "society" or vs "The world" as a "coming of age" story. He almost never has someone coming after him, specifically, or deliberately getting in his way, at least not for very long.
- Rescue Romance: Luna and Maria are in Noir's harem because he's directly responsible for saving their lives, and they're grateful.
- Spell My Name with an "S": The names of the characters change between mediums. For example, Noir's family name changes from Stalgia in the novel to Stargazer in the manga.
- Supporting Harem: Noir and Emma are clearly the leading love interests, but the other girls of the harem give Emma serious competition.
- Top Wife: Emma jealously guards her position as Noir's primary love interest.
- Your Days Are Numbered: The curse, "sixteenth death" kills whoever is afflicted on their sixteenth birthday if not broken. Maria is introduced to the story having this curse, with her "sweet 16" birthday just a week away.