The way points of this running / walking route:
Unizo hotel start
Run down asakusa dori or better run down a side street parallel to it as much as possible
At Azumabashi turn left and then run along the river side. When you can take the steps down to the lower level path right by the river
The lower level riverside path ends here abruptly just before the gray bridge. You need to have taken the steps up to the other path a couple of hundred yards/meters back.
Crossing Meijidori
You can run over this bridge or under it. I ran over on the out trail and under on the in trail as shown
In wet weather the ramp down here at the end is extremely slippery. Just go down the steps and backon the river side
Crossing Meijidori is a major pain. But it is the only bit of traffic on the route. Run back and forth a bit until the little green man says it's safe to cross