On the continent of Septentrio, there are tales of the past when heroes and demon lords fought against each other. There was a maou that ruled over the fertile Kingdom of Grüngard. The imperial family was quite adept at magic and lived much longer than humans. The neighbouring countries feared history repeating itself and attacked, but they were always defeated. Now the kingdom is ruled by the young but skilled Dune Angrojia Grüngard, who is well respected by his people. He has the special ability of being able to control tentacled creatures to defeat enemies. Due to an unfortunate accident, he was put into a deep sleep for many years. During this time, the Kingdom of Rindveld which is full of heroes declared war on Grüngard with the intention of defeating him. When Dune awoke, the attacking forces led by Aria Ashtein had already reached the city limits. He decides to unleash his tentacled minions to defeat them and reclaim his territory.