In this action-packed fantasy manga, a young man burdened with the role of a "Hero" successfully changes his class to "Monster Tamer" without realizing that this transformation would lead him on a journey just as heroic. Many young boys dream of becoming heroes, but not Noa; when the heavens assigned this unassuming young man the coveted "Hero" class, he set off on a journey to find the "Class Change Book" to live a peaceful life on his terms! After all, who want's to slay a demon lord you've never met?! After five years, he finally reaches his goal and opens the book, only to discover that his new class is "Monster Tamer." With his newfound abilities, what adventures await Noa?