What if instead of Kazuma, the world of Konosuba gets the Number 1 cinamon roll of the hero world? Find out in this experiment of a crossover!

Born as a human with the heart of a fishman, Izuku has lived his life dreaming of a day where he can enact his adopted mother's wish to bring the residents of Fishman Island to the surface and live among the humans. However, his own heart holds him back. See as Izuku becomes a hero for not only humanity, but the fishmen and merfolk of his homeland.