Sumo wrestling, make it into a fun game where everyone is wrestling each other. Get a real sumo in and who ever can push over the sumo gets a prize

Sushi cooking class, Geisha dress up/photo op.

When the guests arrive they get to write their name on a name tag that's written in kanji, hiragana, katakana so they know how to spell their name in japanese. Makes greeting and getting to know other people more interesting through a learning process.

I wouldn't suggest a gold fish scooping (I don't believe in animal cruelty)

Get a Enka singer in to perform.

sorry out of ideas now

Sorry I know I can't post consecutively.

Culture experience-wise

Holding Japanese tea parties at a public open space preferably with cherry blossoms or a place that can emanate the same feeling of drinking sake beneath a cherry tree would be awesome, selling cheap japanese street food i.e. teriyaki skewer, take away bentou, those squid balls (see I already need to be cultured about street food)

I think it's a good idea to refer to prestigious universities' Japanese cultural activities.
Harvard University Japan Trip
Columbia University Japan Study Tour
Cornell University Weeklong Japan Study Tour


If you introduce someone to Japanese products, be very careful of imitations, since Japanese cultural products are seriously invaded by neighbors.
http://kaola.jp/2013/11/05/16998/