This Japanese book is a collection of solo piano sheet music of songs from various Studio Ghibli films.  Please see the photos for a complete song list (though it is in Japanese).

Includes songs from:

Nausicaa

Laputa Castle In the Sky

My Neighbor Totoro

Kiki's Delivery Service

Only Yesterday

Porco Rosso

Pon Poko

Whisper of the Heart

Princess Mononoke