Now I'm a Demon Lord! Happily Ever After with Monster Girls in My Dungeon: Volume 9 by Ryuyu

Reborn in another world as a demon lord, Yuki is managing his newly—and accidentally—acquired phantom ship dungeon. At the same time, he’s steadily working on expanding and strengthening his existing territory. Then, one day, he thinks it’s about time for him to stop neglecting his duties as the Dragon King, so he decides to visit the Dragon Hamlet and introduce himself to its residents.

He and Lefi take to the skies to get there, but on the way, they encounter a massive airship under attack by monsters. After helping the humans operating it, they resume their journey and finally arrive in the Dragon Hamlet, where they’re greeted by the elders. He pours his magic into a stela to carve his name into the dragons’ annals as their newest Dragon King, but then...