The manga version of My Room Is a Dungeon Rest Stop is an adaptation of a web novel of the same name; I can find no indication that it has ever been published in print, however, and the web novel does not seem to be legally available in English at this time. Based on its (rather short) first volume, it is a series that won’t dazzle anyone or rewrite any standards for light novel storytelling, but it has a simple and likable enough set-up that I can see it being successful.
Though the concept and mechanics involved share many traits with isekai series, this one more resembles something like Restaurant to Another World in execution: Touru’s front door has become the world-hopping portal, and travel both ways is somewhat possible. That “somewhat” is where the story’s most interesting early twist comes up: though Ria can be brought into Touru’s room, it is still a dungeon room for her. The window which looks out on Tokyo for Touru instead looks out on a dungeon wall for her, and Touru exiting through the window looks like him walking through said wall. (She can’t exit that way herself, apparently, so it’s not an illusion.) Hopefully some world-building on this will be added in eventually, as this is not a common set-up element. That Japanese is “the language of monsters” in Ria’s world is also a very interesting detail which also presumably has some meaning readers will find out about later.
Another interesting twist is that food and drink from Touru’s world can have restorative effects much like potions when used in the dungeon chamber or on people from the dungeon’s world. Proper meals seem to restore health and magic (I couldn’t help but think of the classic arcade game Gauntlet, though the writer is probably drawing inspiration from more recent game examples), while cola functions as a poison antidote and more snack-like items provide temporary boosts to various stats. Both this and the other twists smack of storytelling convenience, as does the predictable reliance on game-like stats once one crosses into the dungeon chamber, but like with the other twists, I can give the story leeway on this if it is eventually elaborated upon.
A third twist is the nature of a slime that shows up. Slimes are the traditional lowest-level monsters in many Japanese-originating fantasy RPG games, and for the most part that’s no different here, though at least one type can apparently spit poison. The twist is that an ultra-rare special white type exists which, according to legend, can mimic human shape and work with them. Maybe someone has been inspired by That Time I Got Reincarnated by a Slime, but it is still a neat idea and both the opening color pages and the last regular page make it clear that the slime Touru finds early on is exactly one of those special kinds.
A second humanoid character – apparently an elf wizard – is also shown in the color pages at the beginning, but this volume entirely involves the introduction of the knight Ria, who is featured on the front cover. She is a very likeable character and ideal waifu material, with a highly attractive character design and charming expressions. However, she is not in the slightest credible as a warrior-type adventurer, even if she is a fledgling one. (Admittedly I am making an assumption on this last point, since her stats have not yet been shown, but it seems likely.) She comes across as much too soft for her occupation and especially much too trusting; yeah, she has been through a tough experience, and Touru has been nice to her, but she is getting remarkably cozy remarkably quickly with an unknown wizard she just met in a dungeon. Some comments she makes suggest that she is at least of noble birth, perhaps even high enough to be associated with the royal family. However, any details about that will have to wait for a future volume. Touru, by comparison, is a standard nice guy who’s at least a bit of an otaku. Why he is a college dropout is not elaborated here but hopefully will be at some point, as he seems to be a resourceful and reliable young man.
The overall artistic effort is appealing and solid in consistent quality but not especially strong, with a reasonable balance between cute and sexy being found with Ria. Her adventuring garb and armor do not seem very practical, but they are pretty much Japanese fantasy RPG standard, so quibbling about that is probably pointless. The production by Seven Seas translates all sound effects and replaces the originals entirely when there isn’t much room in the picture. The actual manga part clocks in at only 119 pages, with an additional short story by original author Tōgoku Hudō taking up an extra 11 pages, including several chibi illustrations at page bottoms; this should be considered essential reading, as it explains a few relevant points that the manga part does not. Add in a couple of congratulatory note pages and you still have quite a short volume by American release standards.
And that’s the main problem here: there is not enough material available yet to determine whether or not this is going to be a worthwhile title to follow. Its positive points are currently being equally balanced out by its utterly generic traits, so I am going to reserve judgment on whether or not to recommend this series until after seeing a second volume.