absolutely the most updated hatsune miku: colorful stage/project sekai crystal farming guide people call em diamonds. people call em gacha funds.whatever it may be, if you want crystals now is your chance.
Another thing you can do is to increase trust rank for each character to at least 2 since they give 50 crystals, it's pretty easy to increase to rank 2 so yeah. Also I would love to know how you tier, please do a tiering guide in the future, thanks!