(阿蘇山) Mt. Aso Hike

Mt. Aso is the largest active volcano in Japan, and with a 25 kilometer caldera, among the largest in the world (wikipedia). The town of Aso is in the middle of this caldera, which is one huge flat spot.

Hiking is already as stroke of luck weather wise, but this has an added factor of volcanic activity - all roads are closed when volcanic activity is high, so if visiting, make sure you have alternative plans if the mountain is closed.

Budget: JPY 1,300 (~USD13)

JPY1,300. Bus, Aso Station to Aso West Station. (JPY650 one way)

Hike Date / Difficulty (Elevation: 1,592m / 5,223ft)

December 28, 2020. I have done this hike as part of a week long Kyushu hikes.
Difficulty:2 out of 5
Route below is around 9kilometers, with an elevation change of ▲698m/ ▽698m
PDF Map Link

When to Go

Throughout the year! EXCEPT for the periods with active volcanic activity. Time wise, take note that the road opens at 8:30am (or 9am from December to March)

Special Notes

The highest point is called Takadake-yama (高岳山), but the viewing point for the crater is Nakadake-yama (中岳山)
Volcanic alert. You may plan and plan, and all the roads may end up closed due to Mt. Aso's volcanic activity. So check the link in advance. But this part of the road can be walked in 20 minutes, so no worries.
Weather check. Just so you know what to expect.
Trailheads. There's three main ones, and the first one even has a big X mark to it, and yet there are hiking logs as of writing (Sept 2020), so I assume it can be accessed.

Sensuikyou (仙酔峡). Google maps pin. Not accessible by public transportation, but can take a taxi from Miyaji Station (宮地駅). It'll take about 11 minutes, 6.4kms, so probably around JPY2,000 one way.
Hino-o-touge (日尾峠). Google maps pin. Not accessible by public transportation, but can take a taxi from Takamori Station (高森駅), which will be 10.2kms, 22 minutes. So probably around 3,000 one way. I do not see any hiking log using this trailhead though, so I doubt this is trail normally used. tldr: don't use it.
Asosan-west station (阿蘇山西駅)/ Asosan-jou (阿蘇山上). Google maps pin. It's about 13.3 kms away from Aso Station, so do not miss the bus as it's not really walking friendly.

Private transport: For those driving, here's the phone number of the ropeway which can guide you to the trailhead: 0967-34-0411. There's parking at the top of the ropeway so you can definitely skip the ropeway if driving.
Public transport: From Aso Station (two stops left of Miyaji Station), there's a direct bus at JPY650 one way. Same schedule for weekdays, weekends and holidays. It doesn't seem like they have holidays.

Mountain huts. Given that the roads are closed at night, I would expect that staying overnight is highly discouraged. But it's also not surprising that they will have an emergency hut - which they do!

Paid: none.
Free: 月見小屋. It's about 25 minute walk from the summit. It's pretty small, but definitely used throughout the year.
Camping: none.

Itinerary

Given the bus schedule, the bus is not possible, unless you beat the Japanese time by 35 minutes. Very likely, but if you miss the bus, call the taxi company at 0967-22-0825. OR, take the taxi going up and start early, then take the bus going down.

10:40am. Bus, Aso Station to Aso West Station.
11:15am. ETA: Aso West Station. Start hike.
01:40pm. ETA: Summit.
03:40pm. ETA: Aso West Station. Make sure to beat this time by 35 mins to catch the last bus.
03:05pm. Bus, Aso West Station to Aso Station.
05:38pm. ETA: Aso Station.

Actual Log

08:30am. Drive, Beppu Station to Aso trailhead. It was a rather picturesque drive, so put the phones down.
11:25am. Arrived at Mt. Aso Park Road. For the day of our hike, the crater viewing area is restricted and the road was closed, and we had to walk an additional 20 minutes (per map time) to the other parking lot.
11:30am. Started our hike. There was a guy guarding the path, and he stopped a tourist wanting to go to the crater viewing area. I talked to the guy, said I'm going to Takadake, and he let me pass.
11:48am. Arrived at the other parking lot, close to the crater viewing area. I skipped that one and took the path to the right, following the trail to Mt. Takadake, the highest point of the mountain range. The trail has practically zero vegetation, and was either volcanic ash (soil?) or rocks. It started flat, and around 30 minutes later the ascent started. There's really one big push, and once you get to the ridge of Minami-dake, the path was relatively flat.
12:35pm. Arrived at Minami-dake (南岳). It is out of the way - there's a rock with 南岳 in yellow paint to the right of the trail, no marker.
12:51pm. Arrived at Nakadake, which is the highest point to see the smoking crater. We took some pictures, and continued on.
01:09pm. Arrived at the summit: Takadakeyama (高岳山). Took plenty of pictures, and started our descent.
02:53pm. Arrived at the crater viewing point parking lot.
03:08pm. Back at Aso West Station.
03:30pm. Drive, Aso West Station to Kagoshima.

The view of the hike we're about to do while we were driving to the trailhead.

Since we were not able to use the park road to the crater, we had to walk. The entrance to the road was cordoned off, but there's a path to the right of the road - next to the pole.

The toll for the road, had it been accessible. There were at least a dozen people on the mountain, so people did hike despite of the volcanic warning.

The highest parking spot, and the official trailhead.

The hike starts with a loooong walk.

And then a rather steep ascent. There's plenty of signs, in this case, there's a yellow arrow sign up on the middle left.

The steep ascent is over! There's a marker to 南岳 on the rock, and the trail is on the left. Nothing there, really, not even a summit marker as far as we can see.