Have you had any success with a good study on Japan (for early elementary)? My boys asked if I would take them to a Sushi restaurant and of course, I can't just take them out to eat without turning this into a cultural study. Lol. I know I can google "japant unit study", but then I come up with lots of stuff. I'd rather do one that one of you can recommend.
Did you try Even Moore? You have to join but they have good resources. I don't have my membership anymore because you can't save to a file for printing at a copy shop. It was killing my ink, but they have tons of study units. I think they may have a 3 day trail. Not sure.
Did you look at Enchanted Learning? When my son was in 3rd grade we did one and I just gathered up all their Japanese stuff and made a unit.
I don't know of a specific unit, however you could always start with a trip to the library. Maybe a book on Japanese legends, Japanese art, Japanese dishes and cooking. Then you can take a trip (if you have one close) to a japanese or asian grocery store. A trip down the candy aisle is a delight, brightly colored packages filled with unusual combos. Then top it all off with lunch or dinner at the sushi place.
Before we moved to Japan I got just about everybook about Japan in the children's section including the cookbooks and art books. I used enchantedlearning.com for some of their Japan stuff. We didn't really do a unit study but my oldest didn't a report for her speech class. She talked about their schools, foods and the geography of it. You can tell your DCs that over here they eat seaweed piecies like they are chips. They really aren't bad. Also rice wrapped in seaweed is pretty good. Also not all sushi is raw fish like I thought it was. Enjoy your unit study.