hi! unfortunately 18trip doesn't have very many diamond farming methods 😭 i'd definitely go through all of the main story if you haven't yet and 3star all omotenashi stages (in all of the categories)! other than that... there's not really anything you can do :') if you have kizuna for a lot of characters you can get 10 dia per novel chapter but yeah... other than that it's just participating in as many events as you can ㅠㅠ