Dude that was so short i loved it two experienced gay couple teach new gay couple how to have sex , wow that's what we call master's teaching lol safe sex is important since they didn't use condom fine either way in fiction.
A young couple of lovers ask for help of a more experienced couple to have anal sex, so that when they do it both feel pleasure, so the couple decides to show them the path.
For sure the art's very beautiful. But.. I'm not sure what's the mangaka's intention as it's stuck halfway. I can't say it aims on knowledge of gay sex as it lacks the important part how Uke prepare themselves. It's also lack of love & passion to make it hawt. Σ(  ̄□ ̄||)