The ryokan rhythm
Check-in is typically 3–4pm, dinner is served at a set time (usually 6 or 7pm, in your room or a private dining room), breakfast 8~10am. It might sound rigid at first but it's designed so you don't need to make any decisions and just relax.
Shoes & tatami
You might be taking your shoes off a lot. You'll remove them at the ryokan entrance, again before stepping onto tatami, and sometimes at restaurants too since many places in this area are still traditional (you sit on a tatami mat — also try not to step on the edges of the mats, which is considered a bit rude). Slip-ons make all of this significantly easier. If you're planning to hike Mt. Yufu, bring proper sneakers (it's not a crazy hike but you'll want a grip near the top). And if you're going to the gorge, some water-friendly shoes are helpful since the riverbed can be wet.
The yukata
Your ryokan will provide a cotton robe and you're welcome — actually kind of expected — to wear it to dinner, to the baths, and around the property. It's a really comfortable way to spend an evening and honestly part of what makes the ryokan experience feel different. Most people end up loving it.
Onsen etiquette
The main thing is to rinse off thoroughly at the shower station before getting into any pool — there'll always be one right there, it's very straightforward. One thing worth knowing in advance: tattoos are technically prohibited at many public baths in Japan. At the ryokans on this list with private baths it's completely a non-issue. For the public options like Otomaru and Gin-no-yu, you may want to cover smaller ones up with waterproof bandages.
No tipping
No need to tip at the ryokan, at restaurants, or taxis or anywhere.
Google Maps
Google Maps is great in Japan, including in rural Kyushu. Download offline maps for Shonai and Hasama areas (for three and five day itineraries) where signals can get patchy.
Convenience stores
Convenience stores are really good here. They have onigiri, sandwiches, hot foods, and coffee, medicine, sunscreen, underwear, shirts, toiletries (mini sets). The ATMs work with foreign cards, and they're open 24 hours. There are 7 just in walking distance from Yufuin station alone.
If something goes wrong
If something goes wrong — missed train, closed restaurant, wrong turn somewhere — find the nearest convenience store or a koban (small police box, usually near train stations) and ask. The ryokan staff will also help you with virtually anything so it's worth asking them for help if you're unsure of anything.
IC card
Add a Suica card to your iPhone or Android wallet before or shortly after landing — it handles subway fares, convenience stores, and most transit (and the vending machines on platforms) without needing cash or tickets each time.
Send your bags ahead
If anyone is coming through Tokyo first, you can ship luggage directly from your Tokyo hotel to your Yufuin ryokan for around ¥1,500–2,000 per bag via takuhaibin (door-to-door delivery service). The bag arrives before you do. This is completely normal practice in Japan and really worth doing — the Yufuin no Mori has overhead storage but no luggage car, and dragging a large suitcase through a mountain town is its own minor misery. YUFUiNFO at the station can also handle drop-off and forwarding if you arrive with bags before check-in.
Cash
Japan still runs significantly on cash outside major cities — Yufuin's better restaurants and most public baths are cash only, as are many of the smaller stops across Shonai and Hasama. Pull out ¥50,000 at the 7-Eleven ATM in Fukuoka Airport on arrival, which takes about two minutes and accepts all major foreign cards. There are ATMs in Yufuin but running short on a Saturday afternoon in a small mountain town is a minor headache worth avoiding. Anything left over spends fine in Tokyo or converts back easily.