After conquering the 【Merujine Seabed Ruins】, Hajime was troubled by the impending separation from Myu as their journey was about to resume. To create memories before setting off, Hajime and the others decided to explore the "Erisen Seven Great Legends" with Myu, but each attempt ended in disappointment. However, during the seventh and final adventure, they encountered a mysterious giant creature and were transported to a world of ruined cities! As Hajime began searching for the lost Myu, he achieved a miraculous encounter there—. Prove your own strength. The "strongest" otherworldly fantasy OVA makes its long-awaited appearance!