The Spirit Master of Retarnia -Conqueror of the Labyrinth-

In the peaceful Kingdom of Retarnia, which has known no war for five centuries, tranquility is shattered as portals to the Demon World burst open, unleashing sinister monsters intent on conquest. This crisis mirrors an event from five hundred years ago, when the "Spirit Master of Retarnia" and his five spirits—Norn the White Spirit, Vesta the Red Spirit, Rusalka the Blue Spirit, Melissa the Green Spirit, and Iris the Black Spirit—fought the demons and sealed these portals. Now, at Queen Sylvia's behest, Leonard, a direct descendant of the original Spirit Master, embarks on a perilous journey into the Demon World to protect his kingdom from impending doom... [Based on MangaGamer]