Yu Okano 
The Unwanted Undead Adventurer (Manga) Volume 3 [EPUB ebook] 

Rentt meets a beautiful woman in the dungeon! What’s Lorraine gonna say?!

After evolving into a thrall, Rentt explores an unmapped part of the dungeon and encounters a mysterious woman. In exchange for his discretion, she gives him a treasure called the Map of Akasha, but before he can learn anything about her, she warps him out of the dungeon.

However, meeting her may just be the least of his worries. On his quest to become a Mithril-class adventurer, he must first pass… the Bronze-class Ascension Exam.

His new life as an undead adventurer is finally beginning!