Seinaru Ken wo Nuitara Onna no Ko ni Natte Shimatta Yuusha no Manga

The Holy Sword is a magical artifact that is said to grant whoever can pull it from its stone their deepest desires, and the power to save the world. A young hero and his companion step forth, and he succeeds in retrieving the sword. His wish is granted, but it wasn't for power or fame... it was to become a cute girl! Now ridiculously overpowered and with girlish abilities to boot, the hero must navigate the joys of womanhood and yuridom while saving the world.