Thank your help I figured out what I did wrong, turns out I just had to use Lili in one overview map battle, after that, I went to talk to her and that unlocked the beach scene. Thank you for your help.
It's the battle strategy part I'm confused about, I have her joined the army yet she doesn't appear anywhere on the beach. Do I need to raise her army level up?
When you say knowledge, are you talking about Chiyo magic knowledge stat? And what places would I take Lili, is that where I make her join the army battle thing?
I don't know why I can't unlock Lili sex scene, I have her in the castle, and all 12 party members, and I have the beach. Could someone tell me what I am missing please?