Make sure that your persimmon is ripe otherwise it will feel like the persimmon is sucking all of the moisture out of your mouth.
Don't roast if your persimmons are ripe! This was so good when I tasted before roasting, and so disappointing after. I used nice, ripe hachiya persimmons. In future, I would skip the olive oil and simply wrap ripe persimmon and a few rosemary leaves with a bit of proscuitto, skewer with a toothpick, and enjoy.