G'day,

I'm no expert, and certainly can't read foreign scripts that don't use English based characters, but I think it may be from Hong Kong, China.

I am basing this theory on the drawing style of the children on the lower, right hand corner of the picture and the 'SONO KONG' label in that vicinity.

Like I said, I'm no expert but to me, the script doesn't look Japanese.
That being said, if I'm wrong I gladly eat my own hat.