Original Run: January 9, 2021 - March 27, 2021 Number of Episodes: 12 Genre: Adventure, Fantasy, Harem Based on the Series Created By: Meguru Seto and Note Takehana
***Warning, the following may contain spoilers for Hidden Dungeon Only I Can Enter. Reader discretion is advised.***
Series Synopsis
Noir Stalgia (voiced by Ryouta Oosaka) is the son of a low-ranking noble. Given his family’s status, most of the upper class quickly dismisses him. However, Noir possesses the incredibly rare Great Sage ability, which grants him the answer to any question.
Having been unable to secure a job, Noir decides to enter the Hero Academy. To make himself stronger, Noir’s Great Sage advises him to search a nearby hidden dungeon.
Inside, Noir discovers an imprisoned woman named Olivia Servant (voiced by Yui Horie). When she was free, Olivia was a powerful adventurer. Since there is no way for her to escape her fate without being killed, Olivia agrees to become Noir’s teacher and grants him access to her skills.
Now, Noir can basically control reality as he sees fit. The catch is, he must spend Life Points to do so. And to increase said Life Points, Noir must engage in enjoyable activities such as eating delicious foods, obtaining material goods, and, most effectively of all, sex.

Series Positives
Uniquely, I have to acknowledge The Hidden Dungeon Only I Can Enter (Hidden Dungeon). Sure, this series wasn’t anything special, and I won’t pretend it was good. Nevertheless, this show was a clear indication that a fantasy setting doesn’t need to be an isekai anime.
Think of everything Hidden Dungeon had; where have we seen them before?
- Video game stats
- RPG elements
- An overpowered/clearly above-average main character
- An ever-increasing harem
Although not every isekai anime has these qualities, plenty of them do, and most could have worked just fine as a pure fantasy narrative. Had you described Hidden Dungeon to me beforehand, I would have been sure it was another isekai story.

Aside from what Hidden Dungeon wasn’t, what of the show itself?
To put it simply, this series was a harmless ecchi anime. It had all the boobs, inuendos, compromising positions, and harem qualities one can expect from such a show. I mean, the main character, Noir Stalgia, got stronger when pleased by sexual encounters (as well as delicious foods and material goods, but you guess which option was more prevalent).
Ask yourself; are you in the mood for something mindless? I know I occasionally feel the urge to watch something that doesn’t require a lot of thought. While that doesn’t sound like a tremendous endorsement, such shows do have their value. Hidden Dungeon was one such show.

If I had to give this series praise for something, I would say the challenges the characters faced were precisely that – challenging.
Was death ever a possibility? No, Hidden Dungeon was much too silly for that to become a worry. Still, characters had to put some effort into overcoming an obstacle. While Noir Stalgia’s – what we will call – Edit ability was laughably convenient, the show never abused it.
The Life Point values to change skills were indeed arbitrary, being lower or higher depending on the needs of the plot. And yet, this story did a decent job of picking and choosing when an edit was affordable or not. Instead of relying on ways to ensure his win (those often cost too much), Noir needed to get creative and combine cheaper alterations to give him an advantage.
There was enough strategy to each encounter to make the action in Hidden Dungeon passably entertaining.

Again, as ecchi-heavy harem anime go, this series was par for the course. If you’ve seen any lighthearted fantasy with outrageous boob-physics, then you’ve seen Hidden Dungeon.
What was even more crucial, Hidden Dungeon wasn’t infuriating compared to other ecchi fantasy stories that aired alongside this show (I’m looking at you, Mushoku Tensei). If fanservice-filled anime are not your cup of tea, then you probably already have a good idea if this series is suitable for you.
But while this show doesn’t promise anything substantial, it certainly wasn’t the worse thing in the world.

Series Negatives
As I write this section, I can feel energy escaping from me. The fact of the matter is, Hidden Dungeon won’t be winning any awards. This was no hidden gem, it was fleetingly entertaining (at best), and if you were to ask me point-blank, no, this was not a good show.
And that is as harsh as I feel this series deserves.
If you are in the mood for an ecchi anime, then that is the only reason why you should consider Hidden Dungeon.

Let’s take a look at the story; it wasn’t memorable.
As I said, it was outstanding this show wasn’t an isekai. I know I have seen this narrative play out before. There weren’t any twists, turns, or intrigue to suck you in or hold your attention. Instead, this series relied entirely on its fanservice, which was exceedingly tame (this coming from a person whose job it is to watch and review anime).
And if that doesn’t do it for you, then good luck making it through half of Hidden Dungeon, let alone the whole thing.

What of the characters?
Exactly, what about them?
Of the leading group, you had the bigged boobed girl, the objectively beautiful girl, the mature girl, and the paper-thin male protagonist at the center of this paint-by-numbers harem.
Now, to Hidden Dungeon’s credit, Noir’s master, Olivia Servant, wasn’t part of said harem. On the contrary, this was the only relationship that had any actual weight. Between Noir and Olivia, there was a strong teacher-student bond. I can believe that if there was one character in this series that didn’t want to sleep with Noir, it was Olivia.

Believe me; if there were something to rage about in this show, I would do so. But there wasn’t.
Hidden Dungeon was a no-thrills harem anime that was everything mediocre you can expect out of the genre.
- A simple story
- One-note characters
- Boobs, just, all the boobs
You would be doing yourself a disservice if you went into this show expecting anything more.

Final Thoughts
There is no shame in admitting you enjoy an ecchi anime from time to time. These shows are not usually known for their quality, but a true gem will shine through now and then.
This is not that sort of series.
Instead, this is a show that goes through all the bouncy-bouncy motions you have seen so many times before.
Although it won’t hurt you if you decided to give it a shot, in the end, The Hidden Dungeon Only I Can Enter can be skipped.
But these were just my thoughts. What are yours? Have you seen this series? How would you advise The Hidden Dungeon Only I Can Enter? Leave a comment down below because I would love to hear what you have to say.
If you liked what you have read, be sure to follow Anime Hajime on our social media sights so that you never miss a post or update. Also, please share this review across the internet to help add to the discussion.
For Anime Hajime, I’m LofZOdyssey, and I’ll see you next time.