Because I, a gloomy person, was invited to a Christmas party where only popular people gather... I didn't feel like going, but when I went... unexpectedly, it turned into a mass orgy!? The girls are getting excited at the party in cute costumes cosplaying as Santa Claus for this day! But, someone mischievously put Viagra in the champagne!? Then it's a big problem! The girls and boys who drank the spiked alcohol also have the Viagra effect added, and everyone is in extreme erotic mode!? I want to somehow help the pure-type Lili-chan I admire, but the girls around me keep attacking me! Everyone is flying high like sex machines, it's a fucking paradise!! I couldn't suppress my horniness, and in the end, it developed into a 10P mass orgy with men and women mixed together! It's the best just to be able to have sex with Lili-chan, but I got carried away and even creampied her, and even I, who had nothing to do with Christmas, made the best memories! But, I ended up dating Wakana-san by chance!! After that, we decided to have a Christmas party just the two of us... but then an unexpected development!?