I can't seem to download it on Android. I have enough space and all, but whenever is do, all it says is "App not installed" can anyone help me out on this?
Free space needed while installing is always twice the file size, that's the most common problem that people have. Otherwise u could try installing through split apk Installer (SAI), it's available on play store and it'll atleast show what the error is due to which the app isn't installing
It is also suggested to NOT install and just use the app Joiplay on the Windows version of the game, this way you avoid any security measures Android has against apps that are bigger than a certain size or that don't come from a trusted source.
So there is like no way to get Happy Harem Endings at all and you must chose only one girl to get it,also if there will be a Truly Happy Endings what will they be like considering what kind of game is this,and is True Ending you mentioned some kind of Ultimate Happy Ending with one girl or harem or something else entirely?
True happiness is not likely, this is a Denpa game, which are notorious for almost never delivering happy scenes and ALWAYS delivering horror in some form or another.
We could expect a bittersweet, not as bad ending, but that is a LONG way away and will likely only be in the true ending.
The path we are on now is the dark path, which will end badly, guaranteed, and next is the single girl purity routes, which could take one of several forms.
Two of the forms with the best chance are A) not happy, but not totally dark like the path we're on and focused on one girl or B) still totally dark like the path we're on, but focused on one girl.