When seventeen-year-old Tatsuo Kobayashi is sent to Hell after drowning in a toilet, he meets the demon Vorrath and is reborn into another world with the demoness Athena by his side. In order for Tatsuo to stay in this world, he must conquer it!

Tatsuo Kobayashi heads to the town of Brimstone with Lilith Bloodsuu by his side. The two are in search of two liches who have slaughtering Adventurers for an unknown purpose. Vexx is left with Athena back in the Demon King's castle and must face his defeat to Zena and Blue.

After recruiting the Undead Twins into Demon's Castle, Tatsuo Kobayashi and his monster servants descend into the depths of a dungeon in search of rare magical items to strengthen the town of Loch. But the group unexpectedly separates after entering the dungeon's thirtieth floor, home to a human colony and demonic secrets.

After his encounter with the demigods Orion and Perseus, Tatsuo comes into possession of a small girl. Tatsuo and company soon come to learn of the horrors that come along with the child's origin. As the child's origins become known, a new enemy reveals itself to Loch as well. Will Loch be able to overcome the possible threat that is the Council of Thrones?

Tatsuo Kobayashi has his hands full with the Council of Thrones. But as the battle wages on, the Seven Heavenly Virtues have a battle of their own to fight. After an elder lich invades the royal palace, the Seven Heavenly Virtues accept the task of eliminating it without the public's knowledge. But things become far more complicated as the elder lich's origins become known. The only hope for the kingdom and the royal family is the Seven Heavenly Virtues, especially Lazarus Lucifer...