Yuji Sano was a normal guy working a soul-sucking nine-to-five job when he suddenly found himself transported to a fantasy world where he restarted his life as a Monster Tamer. After befriending the Slimes, Yuji is quickly able to gain a second character class, ranking up his stats and learning new skills as he encounters one surprise after another.

Reliol, the only other human besides Yuji to possess both “Tamer” and “Sage” classes, has been resurrected into the body of Teaph, one of Yuji’s classmates! Reliol and Yuji decide to team up in order to destroy the Laboratory. Being one step ahead, however, the evil organization formulates a plan that will force the two legendary Sages to fight each other! Who will come out the victor?!