Well... this game was both better and worse than the first one...
It's better in the sense that it has significantly more CGs than the first one did, and more scenes accessible in the gallery in general. It's worse in the sense that I think the systems for this game I worse than the first one. The girlfriend's fall into lewdness isn't really tied to MC's action/inaction, or the player's skill. It's tied purely to the passage of time.
As such, if you don't follow a guide or cheat, then the first playthroughs and their endings are going to be primarily a matter of luck as you learn what stuff is where and how to get it most efficiently. Not to mention figuring out what's the deal with the questions at the start. Whether you want to have as much time as possible, or whether you want her to jump on dick as quickly as possible, then you still have to experiment quite a bit... which is honestly a tad annoying.
That said, after the first playthrough, regardless of which ending you get, the game unlocks a special room on all saves that lets you get basically infinite recovery items, as well as a chest that gets you all the items you need to collect to go virtually anywhere. In theory, this can allow you to reach the ending with any combination of questionnaire choices, which can either trigger the Happy Ending or the Normal Ending (depending on whether the girl is a slut or not, basically).
Hilariously, I was able to obtain most of the endings naturally while messing around to collect events and see the sprite locations... EXCEPT for the Slut Ending, ending 4. I'm not sure what the trigger is for that one, but it might be impossible to achieve if you start off with Yuyuna being a Devoted Girlfriend and as such with no experience other than the MC. Which is presumably the way she's supposed to be given how the first game's True End goes.
One interesting thing to note here, compared to the first game, is that none of the endings are called "True End". I wonder why.
On a different note, man, they really blasted the MC in this one in terms of turning him into a turbo-cuck... If you set her to the pure state, aka the Devoted Girlfriend, then her stats show her as having had sex something like 20 times... and orgasms at 0. ZERO. Nil. Nada. Holy crap. Man, it definitely doesn't sound like the Happy End is happy for her... Guy deserves to be cucked so that poor girl can have a proper sex-life. Sheesh.
Anyway, I'm kind of disappointed that they didn't have any of the peeping stuff from the first game. The guy remains 100% ignorant in this one no matter how much she fucks around. Less endings too. All of them just as lazy as they were in the first game though... so I suppose it doesn't matter that much.