Reading the thread. I feel most people don't "get" this game.
If you want to experience all the H-content, then you need to up (and later manage) her lust, whilst being very efficient in how you play out your days to unlock all the memories (the hints and requirements are listed in the Items tab when you hover over them). Several of the sub ones will require you gain the medals from doing the random activities like fighting crime or killing time ir working X amount of times.
This tab also lists all the main story memories as well, basically, you kickstart it by talking to Blue Sherbet in the hideout, then you can check the memories tab to see what you need to do to trigger them. You're not given a direct location on where to look, as you're meant to figure it out, but you have a hint. Also, all the main story ones are marked by a "!" mark. And you are told what are the prerequisites you need to meet are in order to find unlock them in the world. Overall though, the main story stuff is for the true ending, and not really necessary for the H-content. You can entirely skip it, and it seems the devs intention is to allow you to, as in order to unlock all the main story memories, you need to NOT lose the 4th fight to ANY villain.
As for getting all the H-content, the recollection room tells you exactly how to get it. You can also just progress entirely through one villain's route to get their specific bad end. Every night too, Kei will masturbate once her lust caps out, and you're allowed to automatically progress any villain's corruption. If you want to do all of them, then just do all of them at once.
That being said, it seems the devs intention is to have you play the game, figure out on your own what the real identity of each villain is, and getting their bad end by focusing their area and content, then on a NG+, you proceed to the next one. Over the course of this, you get endeared to Kei (who is genuinely well written imo), and shoot for the true ending once you're satisfied or have all the H content unlocked, by winning all the fights and progressing each investigation.
Overall, it's fairly open ended, but you're not meant to run around like a headless chicken. Game gives you plenty of hints for how to unlock any specific content. You're free to just focus one of the bad ends if you want, or do it all, or ignore it all.
As for what the identities of the villains are:
- Black Muscle is Matsuo the gym owner in the park, you're meant to progress his stuff as Levantia
- Mr. Hypnosis is the cult leader in the Office district inside the big building to the east. You have to join their cult as Kei to progress.
- Lilith is Kei's friend/Junior, Reina, and you can meet her at the University inside the lecture room. You progress it as Kei.
- and the Invasoids are tied to the sketchy doctor in the Entertainment district. You progress it by investigating the sewers as Levantia.
You don't need to wait for the fights ro roll around each Friday to progress the corruption of each once. Once you've done all the Round 2 fights, you're free to just blitz one if you want.