Ohh then you're probably way more competent than me at making games xD Please let me know if you ever publish one tho!
The Yusha quest is tough. You need 4 diary pieces and can only find each in order, the last 2 pieces only available after the credits. The secret is to just retrace your steps carefully to revisit places you wouldn't normally. Good luck ;)
Also, sorry I should've been clearer. There's only one real ending to the game (plus a secret joke ending). By endings I meant to the quests, as a great deal of them have 2 endings (usually by completing it or failing, which is kind of the canon option since it's what I wrote the original novel as. Still left the option to win fights you're supposed to lose since I know some players would try tho xD)