Then, get yourself down to the Keikyu Aburatsubo Marine Park in Kanagawa Prefecture! They have a "shake hands with an otter" exhibit, and it's all I can do to not run to the airport right this very moment.
Apparently, you dip your finger in smelt extract and put it up to the hole in the enclosure, and one of the Asian small-clawed otters will come and "shake" your hand.
So, if you're in the area (southwest of Tokyo), and you want to do this (of course you do), you can call the park for a reservation. It's a very popular attraction, so do be sure to call ahead!