Summit Mt. Fuji (富士山) via Yoshida Trail

Mount Fuji is the beautiful and powerful volcanic icon of Japan. It has been an inspiration to artists for millennia, and in 2013, it was listed as a World Heritage site.  Summiting the peak of this Holy Mountain is not trivial -- the peak is at 3776 meters (12,388 ft) -- but is well worth the effort. The Mount Fuji climbing season is from 1 July to 14 September.  You can technically climb it until October, though they start recommend that only experienced hikers climb at this time and bring mountaineering equipment with them (also transportation to the stations is very limited).  It is not recommended to hike October to June because the weather makes the ascent way too dangerous. 

There are 8 stations up Mount Fuji (the 8th station being the highest altitude) and then finally the summit.  Almost all hikers start their climb at the popular Kawaguchiko Fifth Station.  

If you're fit, you can climb the mountain in a day (they estimate it takes about 5-6h to make it to the top; it took me closer to 4.5h).  If not, you can spend a night at one of the stations on the mountain (you can make reservations for these huts online here).  You can enter these huts to take a break, purchase a snack or water, use the restroom, etc. without reservations. Alternatively, some hikers hike throughout the night so they can glimpse sunrise from the peak.

The hike begins easy and through beautiful a forested area.  Shortly after the 6th Station though, the tree line fades away, and it becomes very rocky and dusty.  From there, it's switchbacks the entire way to the top. The trail is well-maintained and marked, so you won't have much chance of accidentally going the wrong way.  

Once you get to the top, there are some small shops, washrooms and rugged places to get some bowls of noodles. You can walk around the crater of the volcano (takes ~1h on the well maintained and marked trail), which is very beautiful and satisfying after the long trek.

There is a separate way down (easy to find/well marked) on the top of the crater after the short string of huts.  It takes much less time to go down (maybe 2-3h) and converges with the original trail around the 6th Station. 

What to bring:

• water!!  -- they sell water at various stations as you ascend the mountain, but it is VERY expensive, I don't recommend it!
• Layers -- this is a pretty cool hike since you're at such a high altitude and there is wind (without tree shelter) to cool you off.  It's much warmer where you start and cools as you ascend. The sun can be intense. 
• Sunscreen -- the trek up is cool but don't be fooled! The sun is intense. I should have reapplied sunscreen more often and got a BRUTAL sunburn on my legs (I couldn't wear pants for a week!).  
• Snacks -- you will want this. It's a long hike. There is food available at many stations but it is quite expensive and definitely not great.
• Hiking Boots -- they recommend hiking boots, not hiking shoes.  I did the trek in hiking shoes and was completely fine, but many of the staff at the fifth station were appalled and didn't think I would make it.
• Hiking Poles -- this would have helped, and the tourist information center/online/etc says that it is necessary that you bring one.
• If you're climbing at night and/or are trying to see sunrise at the top, be sure to bring a flashlight/head lamp. 

How to get there:

• from Tokyo: Mount Fuji is ~62miles west of Tokyo.  You can take a bus from Shinjuku Highway bust Terminal, which will take you all the way to the Subaru Fifth Station (where the Yoshida Trailhead is).  This bus takes 2 hours and 30 minutes and costs Y2700. You can reserve buses online (in English) here. Be aware that seats sell out well in advance of the climbing season, so try to reserve as soon as you solidify your trip plans.
• from Kawaguchiko (the town at the base of Mt. Fuji): You can catch the bus that takes you to the Subaru Fifth station (Yoshida Trailhead) at the Kawaguchiko Transit station. 

Other things to note:

• the top of the mountain has little gift shops and places to eat simple bowls of noodles. Again, it's expensive, but a spicy bowl of udon noodles at the top of Mt Fuji tastes amazing and feels so fitting.
• Bathrooms cost money! Be prepared to spend a few hundred yen.  Don't think you can find a place to go behind a tree or bush -- there are none. it's open and rocky and theres no other options.  be prepared!
• Some people buy a wooden walking stick at the Fifth station and get it burn-stamped at each station as they ascend the mountain. Something to consider. 
• Some people get altitude sickness from the change in elevation. Be prepared!
• If you'd like to stay in a hut overnight, it's about 5000 yen without meals and 7000 yen with meals

Helpful Links:

• This is a blog by someone who stayed at one of the huts. He has nice pictures he took and documented his climb. It might help you get a sense for staying in these huts if you're interested in that. 
• https://www.japan-guide.com/e/e6901.html
• https://trulytokyo.com/climbing-or-visiting-mount-fuji-from-tokyo/

BONUS:

If you can find a traditional Japanese onsen to relax in after your trek (there are many options in Kawaguchiko in town), soak your muscles and be revel in your accomplishment!