go to the bottom of the post to see how
https://llonelly.itch.io/monster-sweethearts/devlog/164669/big-monster-sweethearts-update
I've already looked at that and sadly it didn't help since I've already did those things, I just finished lien's route and got all of her endings but still can't get the secret one, thanks anyway though hopefully I can eventually unlock the secret route, amazing game btw never heard of anything like it, wish there were more games like this