You can apply them during sex scenes, some of clothing options shows you the list of outfit files to choose from (don't remember which one exactly). But make a backup from your cards before the process. You need that base first.
And then save as.png it on koikatsu party\defaultdata\common\bg, then change the background type to the picture you saved before. Besides the dlcs, what's different between 'koikatu' and 'koikatsu party' (or the jp and the en versions), and i'm assuming you meant to say the dlcs don't work naturally and i need some plugin? I'm still kinda new to windows, and i'm having a hard time finding ways to add mods/import new models into koikatsu.
Steam sell what you can see as an entry point to both, koikatsu and studio. If you installed the dlc, you have to reinstall the hf patch again. Koikatsu has better customisation, especially with mods, and probably (although don't quote me on that) a better pose variety. There is a guide how to buy and install the dlcs.
Koikatsu party is great for creating characters but without hfpatch the steam version is very lacking. Do i need to reinstall everything back? Is there and englisg version of the shortcut lost? Try checking it out if you are hungry for more.
But, you can't have it without the stuff that is sold on steam. Cm has management and character training aspects, variety of events ranging from girls doing stuff like watering plants, dusting and stuff, to girls being decieved, drugged and r@ped on a rooftop by 6 dudes, and in my. If what you want is to make animations, then it is mainly studio that you need. Hello zale, koikatsu party and chara studio are two differents things, but they come togheter.
This game is basically a free demo of koikatsu party. I just got the game and wanted to check out the shortcuts for it but its all in japanese. Drop the.png outfit files to koikatsu party\userdata\coordinate. Hopefully they put more effort into an english version and don't gut the thing.