Hiked October 7, 2018. map number 17 (but you could probably make do without and just use the map posted at the trailhead).
This is a popular day hike and not too difficult. You should be able to complete it in about 5-6 hrs. I took my wife and son with me this time. The parking lot is at Sugadaira Farm (36.5381225, 138.3713279). There are 2 routes up, and you can do out’n’back or make a loop out of it. We were planning on making the loop so it didn’t really matter which route we started up, but we headed towards Mt. Neko to start. This route starts rather steep, but steady all the way to Mt. Neko (36.5490651, 138.3950647). From here, you hike along a rolling ridge line for a hour or so to the peak of Azumaya (36.5415086, 138.4123653).
To make the loop, come back down from the summit towards the direction you came from, skip the wood steps to the south near the summit (36.5408842, 138.4113709, and I reiterate, don’t take these). Instead take the path heading down at (36.5403896, 138.4078847).
Watch out for swampy, flooded areas near the river crossing and a cow pasture (around 36.5361506, 138.3744727). This is probably the only reason why you would want to wear waterproof boots on this hike.