D-Genesis: Three Years after the Dungeons Appeared (Manga) Volume 5 by Tsuranori Kono

Hoping to steer clear of surveillance, Keigo and Miyoshi race to “retrieve” the skill orb at the center of an international power struggle: Otherworldly Language Comprehension. Pursued by teams from across the globe, the D-Powers duo battle their way through the undead hordes waiting on Yoyogi Dungeon’s tenth floor. While they’re experimenting with their powers, a mysterious gothic manor appears before their eyes. Haunted-house hijinks ensue as the pair are forced to navigate between international espionage, a floor of hungry monsters, and a group of guardians unhappy to have guests. But at least some new help is on the way!