Aso is on the JR Hohi line, 1 hour and 40 minutes from Kumamoto by local train (¥1080, change of trains may be required). There is also a limited express, the Kyushu Odan Express (九州横断特急), which makes four daily round trips with no change of trains required (65 minutes; ¥2180).
Kumamoto connects to Hakata in Fukuoka via the Relay Tsubame and Ariake limited express trains, and to Kagoshima via the Relay Tsubame and the Kyushu Shinkansen.
From Beppu you can get there in about 3 hours by bus (¥2950) or 2 hours by train (¥3740)
There are two cable car lines up to the mountain. Aso Nishi (west) cable car station is easily reached by bus from Aso station (¥540 each way). The last bus back from Aso Nishi cable car station leaves at 5 pm. You can also hop on and off the bus at the bus stop near the Aso Youth Hostel. If you're driving, a toll road goes right up to the station and if you're prepared to pay, you can actually drive up to the summit of the crater.
Aso Higashi (east) cable car station can be reached by taking a local train to Miyaji station (2 stops from Aso station) and then walking up the road to the cable car station.
Aso Shrine. An old shrine dedicated to the gods of harvest and planting.edit
Aso Osaru-no Sato Saru-mawashi, 793 Shimono, ☎ +81 967 351341. This theater has man and a monkey stage shows.edit
Aso-san. Five separate volcanic peaks, one of which is still active, are collectively known as Aso-san. The active Mt. Nakadake is the main draw, providing a constant stream of sulfuric steam that occasionally shuts down the area. The other peaks are interesting too however, and provide some excellent short to medium length hikes, with some stunning views.edit
WARNING: The mountain spews sulphurous gases from the crater of Mt. Nakadake. Sometimes, when the winds blow from the crater towards the crowds, the cable car lines are shut down, so you might not be able to reach the summit. They will start operating again when the winds turn - sometimes you will only have to wait half an hour or so. If you want to check before starting your hike, the owner of the youth hostel is able to tell whether everything is in operation.
If you have extra cash to spare or you want to have an aerial view of Mount Aso, you can take the helicopter ride, which is not far from the Mount Aso Museum. It costs ¥5000(adult)/¥4500(child) per person for a 4 minute ride, but the view is astonishing!
Various hiking trails around Aso-san can provide you anything from a nice afternoon walk to a good day's hiking. If you're interested, there's an excellent topographic Aso Trekking Guide Map available, (ask where you're staying,) but the Aso Guide Map available on the mountain shows hiking trails and is adequate for most hikers. The routes around Mt. Nakadake are marked very well; you get a small map with routes and 'You are here' mark every 15-20 minutes of hiking. The best reward-for-effort hike is up Mt. Kijimadake. Take the shuttle to the Aso Volcano museum, and walk to the far end of the parking lot to find the trail between two small teepees. The peak provides an incredible view of the area, and can be reached in 30-45 minutes, depending on your fitness level. (It's steep.)
There are also several hot spring resorts around Aso. Contact Aso tourist information office for more information.
In October, there's an annual country music festival (Country Gold)at Mt. Aso. Distinguished Japanese gentlemen dress in cowboy boots, horse sashimi, American country stars of former decades...all with a smoking volcano in the background.
Besides the usual tourist trinkets you can buy from the Aso Nishi cable car station, there's not much shopping to do around here. Your usual supermarket is a couple of blocks south from the Aso station.
Kojirō-buchi, 1303-2 Kurokawa (Facing the Aso JR station, turn right and follow the road round and over the railway line. Turn right just before the fire station (look out for the tower), and it's on the left.), ☎ 0967-34-0945, . Friendly, reasonably-priced restaurant. Most dishes involve cooking your own meat using a fire in the centre of the table. Generous portions.¥1500-¥2000. (32.939307,131.080796)edit
There are some restaurants and a noodle bar near the station. In Aso Heights, there is a delicious cheese cake. Japanese lunch box can be bought at Aso JR Station. The aso noodles are amazing!!!
Aso Youth Hostel, 922-2 Bochu, ☎ +81 967 340804, . The youth hostel is quite ascetic, but is cheap and the owner is very helpful. No breakfast, but they sell stuff like instant noodles you can have in the morning. They also have a simple Aso hiking map revealing the different trails around the mountain. It's about 20 minutes walking uphill from Aso-station. They have a very small public bath open from 5PM to 9PM. No wifi and to use Internet, you have to use the prehistoric Windows 98 computer in the hall (if it works), or you can gently ask for a network cable if you are lucky enough.Dorm ¥2000. edit
Aso Base, (500m from JR station), ☎ 0967-34-0408, . checkout: 11:00. It is a little pricy, but worth every cent. Minutes from the Aso Station, spotlessly clean, perfectly organized, laundry, nice kitchen, cozy fire, you name it - they have it. You can borrow a trekking map for free, and the staff is quite helpful. Free wi-fi, but you have to pay ¥100 for 30 minutes on the provided computers.Dorm ¥2800, Twin ¥6000, Double ¥6600. edit
Little Asia Guest House (リトルアシア), 3617-7 Kain Aso-mura, Aso-gun, Kumamoto Prefecture, 869-1411, ☎ 0967-67-2155, . checkin: 09:00; checkout: 12:00. This was a really nice family-run operation close to Aso-san. It's easy to get to if you have a car, but you might miss the sign if you're not looking closely. The place was crawling with small kids, but they were cute and well-behaved. The owners were very welcoming, as were the other guests. There is free wireless/wifi available, and they do a family-style dinner every night at 7PM. Guests who want to attend are asked to contribute a small ￥280 fee to help pay for the food. Our room itself was okay. It was a bit damp in the group room, to be honest, but we slept comfortably. The dorm rooms were crowded - there is barely enough space to walk in there with the beds! Though we didn't see this feature while we were there, they apparently have a natural hot spring out back that you can pay ￥300 to use. The wooded lot behind the guest house was really quite nice and if you follow the trail it'll take you to a "secret" waterfall.Dorm ¥2000, Double/Group Rooms ￥2000/person Single ￥3500. edit
Guesthouse Asobigokoro (ゲストハウス阿蘇び心), Kurokawa211 (1.6km from JR Aso station), ☎ 0967-34-0315 (firstname.lastname@example.org), . checkin: 15:00~21:00; checkout: ~10:00. This is a beautifully converted Japanese house. Free pickup from the train station. Cute rooms with a nice kitchen, free tea and lovely English speaking staff. Dorm(Male/Female separated) ￥2,000 / Private room (2~4Presons)￥2,800 (1person use ￥4,000). edit