So I was looking at the gate of steiner sheet music( awesome show ) and I noticed that in the treble cleft in the second bar, there is a natural sign for no reason, or am I wrong? Also how would you play this, like do the staircase with your left hand? I play piano but never finished my lessons so...

I noticed the same thing. There are a lot of mistakes in the transcribing of the music. I tried playing it and it seems a lot harder than the actual song. I'm not sure if this is true this is only a rumor but I think its if you buy the blu-ray disk or the anime/game sound track you get the sheet music to the official piano version of gate of steiner. Can some one confirm this?

Try this version instead: http://sperion.web.fc2.com/score/gateofsteiner_piano.pdf