The Goblin Ero Trap Dungeon (ゴブリンのエロトラップダンジョン)

There are no female goblins.
However, goblins possess powerful sperm capable of impregnating women of other races.
Inside this sealed dungeon, the goblins are doomed to extinction.
Unless some fertile adventuresses can be lured inside, and corrupted….
The Goblin King shall rise again!