I visited Tokyo last December for 10 days, and spent 3 days to hike this trail.
Course introduction from Tokyo government in English here
Tokyo section has 7 courses with around 90km in total.
Some courses overlap a little bit to reach bus stops.
Most courses aren't difficult to hike, designed to be mainly around 10-15km.
Some parts have steep elevation gain to climb up/down, but overall it is not technical.
I find the trail very enjoyable and in good condition. (at least for Tokyo section)
Courses are easy to access by bus or train, signposts are abundant, and the track is generally well maintained.
While this trail doesn't get a lot of hikers,
and I haven't met anybody in several courses. (no bears as well),
The trail actually reaches Mt. Takao, Mt. Jinba, and Musashi Mitake shrine, all popular tourist spots.
One fun part about this trail is that there is a checkpoint for every course.
To prove you have completed the trail (you can get a pin),
you will have to take a selfie at these checkpoints, write a short hike report,
and submit them to the hiking committee BY POST. (for each prefecture)
By completing the whole trail in all Kanto 7 prefectures (1800km in total),
you will get a pure silver pin.
Some might think "oh people can just cheat by taking the selfies and leave".
Most of these checkpoints are located up in the mountain inaccessible to cars and bikes.
So you still have to get to those remote spots on foot and leave.
I am the 1198th person to complete the Tokyo section.
A report from 2015 says the hiker is around 700th.
That's how few people actually hike this trail. (Or to submit proof)
Even for locals, most will take 3 to 4 years to complete the whole Kanto trail only during weekends and holidays.
I plan to complete the Kanagawa section this year in 2 separate trips.
And maybe someday I will complete the whole trail.
by iwashimelon