I used to pay to run marathons but eventually realized, “I’m paying a hundred bucks for a T-shirt and orange slices,” so I started doing them on my own. Two good courses: follow the winding path of Shirakawa (don’t take route 57! It’s less pleasurable and cheats on the distance!) over the Kitabypass bridge, then follow the rail line (called 杉並道り) until you get to Milk Road 入り口, where, conveniently, there’s a 7-11. Get your beverage of choice (don’t forget to bring money, especially in the case that you get injured and have to take a taxi home) and return on the same route. That’s exactly 42 kilometers from my house in Oe. A second is a bit more challenging but more beautiful: the farm road up to the peak of Mt. Kimpo. Don’t take the main road - too many cars. You’d seldom see a single car on this route. It’s all paved and lined with delightful springs where you can hydrate (and, as always, there are household hoses). Be aware that the slope is deceptionally gradual at the start, but that changes quickly. I don’t know the distance, but the slope is enough. Late autumn is a good time for these types of adventures. And don’t forget to bring money just in case. - William