If you're looking for manga similar to The Otherworlder, Exploring the Dungeon, you might like these titles.
One sunny leisurely day, a woman visited my house and asked me if I were interested in managing a dungeon along with support from goddess. But of course, I refused. Eh? Shouldn't I ignore a person in trouble, moreover if it's a beautiful woman? No way! That's too bothersome, and why do I have to do that? I'm perfectly satisfied with my comfortable life now, throwing it away is just overly stupid...... ...sigh, fine, so it's go to another world, become a dungeon master, manage a dungeon and deal with the Mana circulation problem? Understood, but how to do it?
One day, an ordinary high school student is transferred to another world. He raises his level in the other world, successfully defeats the Demon King, and saves the world! With his strongest status, he decided to return to his own world. However, in the world to which he returns, a new “dungeon” has appeared. A modern dungeon fantasy where the former hero becomes a warrior, delving into dungeons created in his own world!
Former black company employee, Jiro Tanaka leaves his job due to overwork. In his home, he founds a job recruitment template which is from another world company. The job is to test the dungeon created by the demon king. There, the days of diving into the dungeon as a "dungeon tester" were waiting for him to complete the dungeon that even the hero would not be able to clear. He has a hot dark elf boss who has an amazing ability "Magic resistance".
Hiro Bouchi is a high schooler who was friendless, alone, and always fiercely bullied. But one day, the world undergoes the "dungeonization" process and completely changes! In the middle of the chaos, a new skill awakens in Hiro: "Shop". He soon discovers that it's a unique skill that can be used to purchase anything from food and daily necessities, to completely unrealistic, fantastical items!
There has to be a catch when a deluxe rental property is this cheap–and this one connects to a perilous dungeon in another world! Far from being dissuaded, Touru jumps at the chance to sign the lease, hoping to go from high school dropout to big-time adventurer. He soon encounters a stranded knight: a gorgeous young woman named Ria. Touru rescues her and takes her back to Earth, where she promptly mistakes him for a Great Sage, seeing normal things like running water for evidence of his powerful magic. Touru may dream of heroism, but first he has to figure out how to share an apartment with a cute girl from another world!
God left a dungeon in the hands of a boy known as the Demon Lord. After receiving multiple blessings from God, let’s start my life as a Demon Lord! …Or that’s how it was suppose to be, but God messed up and created the worlds’ weakest Demon Lord ever. To continue living, I have to continue making dungeons.This story is about an idiotic protagonist, a lonely demons’ child, an Undine who lives in a bathtub, and a princess who fell in love with the Demon Lord, even though she was human. A story that all unfolded during a bath.
One day, Nagayuki Karasumaru discovers that his closet contains a cavern linked to another world. In that cavern, he finds small creatures on the verge of death. Upon saving them, Nagayuki notices he has become a dungeon master!
Rick, an alchemist who was banished from the strongest heroes' party, is wandering the wilds alone, when he saves a beautiful woman. It turns out that she is a dungeon spirit! Rick makes a contract with her and becomes the dungeon master. Now he is determined to create a dungeon that will defeat all the heroes!