Ryo Mihara dies in Japan at twenty and wakes up in the world of Phi with an affinity for water magic, the only thing that lets him survive its monster-infested frontier, and a hidden Eternal Youth trait that gives him decades to work with. This opening arc follows roughly twenty years of that slow climb, one battle and one lesson at a time, before a chance meeting finally pulls Ryo out of the wilderness and into the affairs of the wider Central Provinces. This light novel is the source material behind the ongoing manga adaptation.