The Unwanted Undead Adventurer Novel Volume 4 was written by Yu Okano and illustrated by Jaian.

Rentt Faina, undead adventurer, reaches the next stage of Existential Evolution and becomes a lesser vampire!

Now short on funds, Rentt sets off to retrieve items necessary to craft equipment for his disciple, Alize. He heads to the New Moon Dungeon with his faithful mouse familiar Edel in tow. Rentt cuts a way through lizardmen and forest wolves, and even defeats the terra drake in the boss chamber. But as he presses on, he stumbles upon a legendary monster—an earth dragon!

Meanwhile, a Gold-class vampire hunter and a saint show up at the Stheno Company. They’re investigating the rumor of a certain adventurer being a vampire...