What Can't Be Left Behind

When an Isekai story ends, it usually is a happily ever after type of story, and what happens after is generally considered not the problem of the current character or the author. Yet, realistically, a journey such as that should leave deep wounds on a hero's psyche, especially if they are a humble teenager, as most stories depict. When a group of such heroes is allowed to return home after their adventure, they have a newfound appreciation for life and an overall positive outlook after the life lessons learned during their journey, but after enjoying their new and brighter life back home, they realise their earlier journey was simply a warm-up for what is to come. When their own home is besieged by a threat similar to the one in the fantasy realm, they find they weren't the only ones who were summoned for an adventure, and they also find their world and many others are far more connected than originally thought...