That Time I Got Reincarnated as a Slime

That Time I Got Reincarnated as a Slime is a light novel series that started in 2014 and recieved a manga adaptation in 2015, along with an anime adaptation in 2018.

OVA 1
The characters of the show all go to a lake in swimsuits in an attempt to recover sand to create a cushion. The gang all get caught in a monster's tentacles however which deteriorates everyone's clothes.