I just checked into it. It actually costs $10 a month paid through a patreon subscription.
if you want a one time payment I suggest waiting for it to be released on Steam
Note: all episodes 1-10 on itch are free to download now
The walkthrough is available with $5 tier on parteon
But you can also just do a save before each choice then skip through to the end of that episode to see your points update
P.s. I'm guessing your missing the good ones for her. To get them easily don't mess around with the others and try to just be nice to her, forget corruption some will come along in that path
One more announcement Az has announced there will be a steam version released before working on episode 12 and that will be updated. But it may be a year or more before it's released
Post with more info https://www.patreon.com/posts/situation-report-113073298
Another announcement for everyone the game is available on a new website and I highly doubt it will be updated here
https://www.patreon.com/posts/oppaiman-store-111311767
The store website link is in above post
announcement for everyone waiting here for the next update
The dev has decided to raise the price to $10 tier on patreon so I don't know when it will get released on here
But at any rate it won't be free on here once it releases
Post with above announcement on patreon https://www.patreon.com/posts/times-are-111185585
Update drops on itch in roughly 2 weeks at time of typing this it is available to anyone who has pledged $10 or more on patreon
Also you pay more you get access to it sooner and if it wasn't mentioned on patreon you would know nothing about an update dropping soon
PLEASE have a little faith in that it's still being developed and have patience for Pete's sake it's a high quality project and it COULDN'T be so if it was rushed