you DO NOT need to lose to get the item. it still available in the drawer next to the bed you wake up in, simply grab it after you fight the optional boss for the charm that supposedly prevents hypnosis
the optional boss you mean matis?
yeah.... that guys had the most random pattern than any enemy,not even compete with the actual boss in this game.
i had to save scum many times only because his attack is rng.
its like the developer make him skippable because of how rng it is,but losing to him will get one scene locked (because you didnt get charm from him).
after many save scum, heres what i know
once he charging theres an chance he will use stun in next turn instead of using the charge attack,BUT sometimes it use charge attack instead of stun.
using item (healing) will cause him to use stun on you.
use guard on his charging attack 3 times,will cause him to use stun on you too.
you mostly die from matis in 3 turns without healing.
and sometimes stun can last for 3 turns... so,yeah... you need alot of save scum or getting lucky