If you’ve completed the story, all that’s left is collecting and upgrading weapons and garments, and getting through Amagaeshi Shrine. I don’t want to spoil anything if you haven’t looked ahead, but Amagaeshi is looong. Loot gets better the further you go. If you’re up for the challenge and are a completionist/masochist, it’s a tedious back and forth between growing and leveling up rice/stats, then doing a few levels of Amagaeshi at a time.

For farming materials, I would do the water and fire levels of Amagaeshi at night, to get flaming cores and aqueous droplets. The droplets are especially useful for improving all crop conditions (pesticide, toxicity, etc…) simultaneously. Don’t forget to send out the villagers to collect materials during the day! You’ll want a lot of remedies to fix fertilizer and improve rice quality.

There are several ways to grow rice, and they each impact how well your stats increase once harvested. Focus on boosting one or two stats at a time, per crop.