When you first get off the train (at Shinjuku most likely), you'll want to stop at a bathroom. Be prepared for long lines even here! The women's line was far shorter than the men's, but still about 1/2 an hour. On the course, the bathrooms were sometimes half a block down a side road and there was quite the wait. When you get to the race start, there are bag trucks that correspond to a number on your bib. You hand over your bag and they take it to the finish. It's just like other marathons.
Just when you're about to throw in the towel, they give you one. Last year it was raining at the finish, so the towel was very welcome.
After you turn over your chip, collect your finisher's medal, towel and various other goodies; you make your way into an enormous room where your bag will be in a holding area for you. Those are some of the bags of runners still out on the course.
The finisher's medal. Not very interesting, I'm afraid. Looks the same as last year.
They have water and sports drink on the course as well as raisins, bananas, umeboshi, M&Ms, and Anpan to name a few. There are also plenty of people who bring out their own stuff. I saw green tea, miso soup, Sake, plenty of candy, pretzels, onigiri and lemons. I have also seen hot noodles.