so I beat the game and have purchased all the power-ups.... I was super cheap. What I did was play in window mode... I would mouse drag the window to a super small size and then leave my mouse over the window, the attack space gets shrunk to a point where your mouse cursor's hit box is almost the same size as the space the attack hands spawn in.... so you auto-block everything. Every attack you block generates special power bar points... I would wait for a few minutes hit escape to pause and drag the game window larger to check how much power I had. Once I got around 5 points for special attacks I would unpause the screen at a slightly larger size so I could kinda see the blue circles to attack (since you have to reduce her guard before any sex attacks can occur).
I recommend: ペロペロ-tongue attack (it costs 3pts to activate)
ロターlittle pill shaped vibrators (1pt to activate and can activate 3 times)
スーパsomething (my japanese is crap)- it charges your regular touch attack (costs 1pt)
マシンターチ-machine touch basically rapid slap/grab, only used during the blue circle touch time (1pt to activate)
moonspeak +1 (costs 40pts in powerup menu and is only item with '+1' in the name, this gives you an extra 'life' so you won't lose after she sucks you off the first time)
It's hard to aim the items but go for the clitoris and/or the belly with items then finger/rub the holes when you have her 'stunned' (which is called DOWN).
Every two orgasms she removes a clothing item (though you can pay special attack points to remove articles if you want.
I recommend waiting till after the first orgasm. Then pay 2pts.... 1pt for ショツ (panties) and 1pt for パンツ (pants/leggings), if you wait it will be about 6 orgasms until you can stick things into her which is alot of nipple and clit rubbing.
I needed 4 'lives' to make it to the end of the sex battle game.
When you beat the sex battle mode it opens a 'love-love' mode. There is one power-up you can't buy until you get max lvl in love-love mode.... you get points in love-love mode from stimulating the girl, though giving her orgasms is inefficient because she'll get a mind blank or something which forces you to wait 15 or so seconds for her to recover and resets all the items etc so you have to re-apply everything.
Anyways, that should be all you need to know to beat this game. It took 4+ hours for me to get all the points needed to buy all the power-ups. It doesn't take that long to buy the power-ups I listed in this guide. The 100pt power ups are too expensive to use in sex battle mode (20pts to activate) though they maybe best as they are mostly different styles of rope work so she can't attack you (I don't know if the ropes stay on the girl or if they reset when she orgasms like all the other items)....
Also, getting 12 orgasms on the girl isn't efficient for earning powerup points... you usually generate 100pts for the store by the end but you'll get about 40 just by getting 2 or 3 orgasms.. so for time management don't bother getting to the highest ranks if you just need to buy stuff in the 'store'
In the 'love-love' mode you can get her to do any sex attack (like sucking your dick or handjobs) that she used on you during sex battle, I think there are two or three options that I don't have because I didn't let myself get caught at each 'stage' to see which handjob variant she was using or if she sticks your cuck in her butt at somepoint (I unlocked vag sex but no back door). To be clear you can manually buttcuck if you buy the おちんぽ power-up but there is an auto mode that is unlocked if she 'attacks' you with it during battle mode.