I ran it in 2016, although flew over from China, where I'm based, so time difference wasn't an issue. I believe the course has changed a little since then too. Started by the metropolitan government building, went through Shinjuku and past the Imperial Gardens, then down and up through Shinagawa & Ginza before crossing over to finish on Odaiba. I heard they tweaked it a bit, not sure how much.
I have since run a little quicker, but Tokyo was the best marathon experience of my life. Great expo with a bunch of freebies, and extremely well-organized with a very scenic course and a huge amount of other runners and deep, supportive crowds almost all the way. The course back then was gently downhill for the first 10km or so, with a couple big bridges right towards the end which hurt a bit (Odaiba is very empty compared to Tokyo proper).
I ditched an emergency blanket at the start line and wore gloves the first 10k or so, then threw them into one of the many bins staffed by volunteers. Drinks stations all had both water and pocari sweat (very popular isotonic drink here in Asia) and there were bananas and maybe other food available too.
I can't recommend it enough - make sure to get there early since the start area is very crowded, but everything is superbly organized and the sights and crowds are great. I fully intend to run Tokyo again one day. If there are still bridges towards the end, go easy on the downhills, but it's otherwise a pretty flat course.
One word of warning for afterwards - the Tokyo metro and train system is very comprehensive in its coverage, but the stations are sprawling and don't always have escalators - be prepared to suffer through staircases or take long-ish detours to find elevators. I trashed my quads (I live and train in a pancake-flat city so long downhills in marathons royally screw me) and was in a world of pain limping around train stations the next two days.