Magical Summer Kaiketsu Tenshi Execute

Two deities compete since ancient times. If Guardian wins, then humanity continues to exist. But when Constructor takes over - humanity is annihilated followed by birth of new life on the Earth.

Main character's grandmother passes away leaving him public bath complex. Then Guardian Riruka arrives with the mission to save life on the planet and occasionally causes huge destruction on the landing point partially demolishing the baths. Protagonist agrees to help her prevent global annihilation. He forms a team of acquaintance girls to develop public bath business and confront enemies together.

[From vndbreview]