Io

Io is one of Jupiter's 79 moons, being the closest one to the planet. It is also one of the locations where the fight between Saitama and Monster Garou took place.

Monster Association Arc
After being sent flying from the recoil of their own Serious Punch collide, both Saitama and Garou land on Io. The fight between them continues on this Jupiter's moon. After Saitama uses two of his serious moves against Garou, Serious Table Flip and Serious Sneeze, Io is badly damaged. Later on when Saitama time travels to the past and defeats Garou the moment the latter was confronting many heroes on the surface of Z-City, all the damage done to Io is undone due to time being reversed.