Manga I Became the Demon Lord so I Created a Dungeon and Spend Heartwarming Time There with Non-Human Girls

Before I knew what was going on, I became the new Demon Lord and guardian of the dungeon. Now I found myself in an extremely dangerous world filled with giant monsters that walked around me. Each of them is fighting for their own existence. At first I wanted to do some development in the dungeon so as not to let myself die, but suddenly I realized that I am having a great time here. How did this happen?

The main character is a guy named Yuki, who is forced to live in this world. Thanks to his keen senses and instincts, he has a very colorful time with a very cute dragon girl named Lefi, as well as a vampire girl. Almost always, the guy just laughs, although sometimes he has to be angry, but he enjoys his new life, and also protects the core of the dungeon.