Crystal Peak

[Sagertooth]

I'm in Crystal Peak with no lantern and have no idea how to get out. Should I just restart the game?

[Hoshikudaki]

Is your save at the bench in the dark room? I think you can get back to the forgotten crossroads by going left and through a dark tunnel(toll gate is on this side)

[Rei Scarlette]

You can't operate the toll gate while the room is dark. There is one on the other side too, allowing you to access Crystal Peak early if you buy the lantern.

Anyways, there are very few dark rooms in Crystal Peak, and if I'm not mistaken, you don't have to actually go through that dark room with the bench. Go left for a bit then upwards.

[wataniyob]

It is possible to exit Crystal Peak without the lantern after getting the ability in that area, but you have to go through about 70% of the area to get the ability so good luck exploring!

And as someone previously mentioned, there are no required dark rooms in Crystal Peak to get the ability.