It's been ten years since Rentt Faina, a down-on-his luck Bronze-class adventurer, set his eyes on becoming Mithril-class. Unfortunately, Rentt finds himself helpless when confronted by a legendary Dragon in the Labyrinth of the Moon's Reflection... and is summarily eaten. But Rentt has miraculously reawakened... as a Skeleton?!

Rentt Faina has successfully overcome the menacing Tarasque standing between him and the Dragon Blood Blossoms he seeks. But then, in the depths of the Swamp of Tarasque, a well-dressed man appears before Rentt, proffering a quest of his own on behalf of the highly-revered Latuule family... Offered an exceptional reward for the collection of Dragon Blood Blossoms, Rentt visits the Latuules, only to find himself trapped in a maze! Seeking a way through to reach the Latuule family manor, he stumbles across an opening with beautiful roses and...a table with teacups? “Are you giving up?” Will Rennt make it out undead enough to achieve his objective of becoming a Mithril-class adventurer?! A young girl's invitation to tea-time may be Rentt's only means of escape!

After Rentt senses something wrong with his familiar, Edel, he and Lorraine leave Hathara and return to the city of Maalt. There they find the city on fire and crawling with thralls. Rentt finds Edel safe beneath the orphanage and learns through him that a single vampire might be the cause of all the chaos. Just as Rentt goes out to help rid the city of the thralls, he runs into the last person he wants to see in this situation—Gold-class adventurer and vampire hunter Nive Maris!

With the help of Lorraine, Isaac, Laura, and the rest of his companions, Rentt defeats the vampire Shumini after he attacks Maalt. However, in order to take control of the new dungeon, Rentt has to turn Rina into a vampire and make her his familiar. Both Rentt and Rina have leveled up, so Isaac suggests they try out their newfound abilities. He also offers to teach them about a vampire’s most notable skill: Division. Not everything goes as expected though, because while they were supposed to transform into a bat, Rina transforms into a cat and Rentt into a...tree? Meanwhile, people are flocking to Maalt to study the newly formed dungeon. Not to be left out, Rentt and his companions set out on their next adventure to explore the dungeon’s secrets! Fighting powerful monsters, solving countless mysteries, and becoming stronger! The adventures of Rentt, the undead adventurer who aims to become a Mithril-class adventurer, continues in this thrilling ninth volume!

Now that the West has suddenly gained control of powerful new technology, the future is looking grim. Meanwhile, Rain's friend Athly has worries that she's keeping from him. How is everything connected...?