Gifu Works of Kawasaki Aircraft Industry, now Kawasaki Aerospace Company, was Kawasaki's IJA fighter factory.http://en.wikipedia.org/wiki/Kawasaki_Aerospace_Company
It was next to IJA Kagamigahara Airfield. Today JASDF Gifu Base still use this airfield and Kawasaki's work is there.http://en.wikipedia.org/wiki/Gifu_Air_Field
As another piece, I must explain about Seinen Gakko. I have made an explanation in another thread.viewtopic.php?f=65&t=148392&p=1664746&hilit=seinen+gakko#p1664746
The bag reads:
Fragments of memory on our schoolhouse and dormitory
Gifu Seinen Gakko, Kawasaki Aircraft Industry
So it is a collection of pics on school and dormitory Kawasaki maintained for its young workers in Gifu Works. A leaf you showed seems a letter to a worker (三宅寿彦 Miyake Hisahiko ..pronunciation maybe) in Shotokuryo, stamped as 26 May 1944. It is from his elder sister Toshie (としゑ). Her family name is hard to read but not Miyake. She seemed married. The leaf says her family were fine and busy farming season began. Their parents were also fine and if he was allowed to go out of the factory she asked to come to see her.
The last pics are Shotokuryo and/or the school. The right is a shrine in the school.