Irojikake Quest ~Inma Yuwaku to Roraku~

The protagonist, the Fire Dragon Hero, sets out on a journey to defeat the Demon King with his childhood sweetheart Finne and his best friend Gard.
Along the way, succubi tempt him in all sorts of ways , leading to betrayal and infidelity , the breakdown of friendships between the group, and the collapse of the protagonist's own army.

The story depicts everything from the setup leading up to the temptation to the ending after succumbing to temptation.

[Translated from DLsite]