DISCLAIMER: This project is an effort to decompile and fix an existing plugin that was not written by me.
The plugin was originally published on 2ch by an anonymous user.

Replaces fades between animations in Koikatsu with animated transitions

• Afterschool DLC
• BepInEx 5.0.1 and above

Download CrossFader.zip from the latest release then extract it into your game directory (where the game exe and BepInEx folder are located). Replace old files if asked.
CrossFader.dll should end up in BepInEx\plugins directory.

Press F1 to access the plugin settings at the upper right of the screen

• Enabled - Choose when to enable crossfade.

  • On - Enable always (Default)
  • VR Only - Enable in official VR Only
  • Off - Disable always

• Debugger Crash Workaround - When not in official VR, disables crossfade in 3P intercourse to prevent potential game crash. See Notes & Limitations for more details. (Default: Enabled)

• Since the vanilla game has no fades at all between animations in VR, this plugin is extremely useful to prevent sudden and jerky transitions when in VR.

• Animation fades are disabled by default during intercourse in two females 3P mode as a workaround to prevent the game from crashing when running with the modified mono.dll for dnSpy debugging (Official VR is not affected by this workaround).
  If you'd like to disable this workaround outside of VR, disable the Debugger Crash Workaround option.
  Please note that this is generally not recommended, as if your game starts crashing after changing this config you'd have to manually change it back to true in BepInEx\config\bero.crossfader.cfg

All credit of the plugin up to version 0.1 goes to the unknown developer who made this plugin.