Synopsis

The chapter opens with the protagonist exploring a ruby-veined dungeon connected to the Baskerville family and the Devil's Constellation Beelzebub. He encounters the journal of two brothers, Abel and Cain, who were trapped by a riddle regarding entering as one, becoming two inside, and leaving as one. The protagonist realizes the riddle's answer lies in shadows, a concept the brothers failed to grasp. He successfully solves the riddle and discovers the relic, the demonic blade named Beelzebub.