Contains spoilers for Dies Irae!

On their stroll back home in World War 2 Berlin, Lotus and Anna are caught in the middle of a brawl between two ashen monsters.

From MyPersonal-scan:
From his late grandfather Viscount Disward, Huey has inherited The Mystical Library of Dantalian, a collection of powerful Mystical Books demonic and supernatural. Together with the dark and mysterious Dariane, they pursue Mystical Books scattered across England. Their adventure begins here.