The Dirty Way to Destroy the Goddess's Hero, Vol. 1 (light novel): Damn You, Heroes! Why Won't You Die? (Dirty Way to Destroy the Goddess's Heroes (Light Novel))

Summary

Fed up with cocky heroes always looking to save the day when all he wants is to find delicious treats for his cute daughter, the blue demon king of the underworld calls upon a young boy--Sotoyama Shinichi--for assistance. Once the two make a deal, the king resumes his visit to the human world until he realizes he may have chosen the wrong person for the job...