Need help finding a Hentai animation

[HentFind]

It was quite a long time ago so some of it might not be 100% correct. But I think that it was an animation from a studio cause it looked pretty good (probably not fan made) but the storyline was something like this: There was a pale slime thing with tentacles and it was rolling/moving in a forest/wood and it hit I a girl wearing like a school swimsuit and it grabbed her. I think there was another girl on the slime monster and it started to touch both of them. Think they are all like high school students or around that age. A man who I think they knew came and fingered the girl and the squirting caused the slime to get burned so to help them, the man started having sex with them while they were tied up/help by the slime. Once again I forgot the exact story line so this could of been like a small part.