Well, 'nidome no yuusha light novel' could potentially revolve around a hero who has to face some sort of resurgent evil or perhaps a new set of problems in a world that has already been through some sort of upheaval. Maybe the hero has some special powers or abilities that he has to use in different ways this time around compared to his first heroic deeds. There could be new allies and enemies, and the story might explore themes like redemption, growth, and the price of heroism.
Since I don't have full knowledge of 'nidome no yuusha light novel', it's hard to say precisely. However, light novels usually tell engaging stories. It might be that the 'nidome no yuusha' (second hero) has to deal with the consequences of the first hero's actions. There could be a power struggle, a mystery to solve, or a relationship drama. The novel could also delve into the hero's internal struggles, like self - doubt or the fear of repeating past mistakes, while on a quest to save the day once again.