no, dont do that. if you tear out your hair, you wont be pretty anymore!
but neways, about that demon realm. I got down quite a bit and didnt know how much further I could go, so I think I just left.
You dont have to go through that place to finish the game.
Only reason thats there is to unlock a few things like a minigame and to get the bishimon(sp?) sword.
and btw, you should save up on medicine`s. you`ll probably need em later.