How to give yourself hand pains while playing a children's mobile game haha

All I do to grind Y-Points is playing on an event stage over and over, and just spamming away all my puni. This makes it more likely for point balls to drop, while also not damaging the enemy too much. I tend to get 10-12 Y-Points per round on average, though it can range from anywhere between 2 to 20+.

I personally grind on Event Stage 7 (Mayone), since she has a decent soultimate to level up. I'd recommend grinding against a yokai that would either be useful at a high soultimate level, or that you can just barely beat (giving you more time for point balls to drop. The fastest method I found for removing puni, at least for me, is by alternating taps between my index and middle finger (1st and 2nd finger), whereas point balls I just spam tap with my index. While other tapping methods may work better for you, that's just how I do it.

Peperon (or any point ball drop rate up yokai) helps a huge amount with grinding, and is definitely worth the y-points needed to buy them. Obviously, flat out Y-Point boosters (like Sgt. Cinderella and DK Chup in this event), are helpful as well, though are usually harder to get.

One thing to be careful of if you choose to copy my method is that, due to the nature of it, you could be at risk of minor hand injuries. It goes without saying, but PLEASE be sure to take a break every once in a while. Whenever your hand starts to hurt, just take a few minutes break. It's better to miss out on one or two rounds of Y-Points, then it is to get something like Carpal Tunnel and be unable to play the game at all.