Suika (Watermelon) Road Race
This is a 10K race in Tomisato, Chiba prefecture (out near Narita).
Yes, there is LOTS of watermelon. All you can eat after the race.
However, it is a long trip to get there. And the year I ran, it was very hot. Not good for running, but good for eating watermelon.
If you don’t mind getting up early and want to do a fun race, this is a good choice.