You should check some of the different versions I've uploaded, some arrangement are easier for some songs.

I recommend Aozora Pedaru, Harukaze Sneaker, Hero, Love so sweet, Pikanchi double, Truth.

My favorite to play is Hitomi no naka no Galaxy, it goes really well on the piano but it might be a little difficult for a beginner. There's an easy version of truth that you can check, it sounds really good on the piano too ^^