Mature Content Description

The developers describe the content like this:

This Game may contain content not appropriate for all ages, or may not be appropriate for viewing at work: Nudity or Sexual Content, General Mature Content

●This game is a work of fiction!
Any names, organizations, locations, or events appearing in this game are fictitious. Any resemblance to real names, organizations, locations, events, etc. is purely coincidental.
This game is only intended for mature audiences of ages 18 and above. The purchase and play of it by minors under the age of 18 is expressly forbidden.
All characters appearing in this game are over the age of 18.

About This Content

After Party is a massive expansion to the highly-praised Koikatsu Party!

◆8 New Personality Archetypes to Fill Out Your Sexy Anime Pantheon!◆
The following character personality archetypes have been added:
・Athlete
・Angel
・Seductress
・Extrovert
・Dominatrix
・French Girl
・The Brit
・Robo
All of these personalities are unique, quirky, and fun, so give them a shot! The world of Koikatsu just got a whole lot more colorful!

◆Tons of New Clothing and Hair Options!◆
"Lots of new clothing and hair options have been added to character customization, from the Wedding Dress to the Poofy Neck Parker, the Straight Curl (paradox!) to the Long Side Messy.

That's only the beginning, though! Tons of other new content has been added for you to explore. Fiddle around with all the new customization options and give your waifu that flair you know she deserves!"

◆New Sex Scenes! Live the Dream With Threesomes!◆
"You've been waiting for it, and we've got it!
New sex positions and categories to play with!

I mean, who doesn't want to get a friendly little orgy on now and then? We've got a whole new Threesome Mode to scratch that itch you've got for twin twin-tailed tsunderes! Grab best girl, then grab second best girl for good measure, and go have some sexy fun times!

We hope you enjoy your After Party!"