Ryugu is an excellent modern ryokan in North Amakusa. Situated just after the 4th bridge of the 5 Amakusa Bridges, it commands a spectacular view of Shimabara Bay and is a popular wedding venue. The staff's English is limited, but they make up for it with Wifi, iPads and Google Translate! First time I've seen a Japanese hotel employ technology this way and it works wonders for communications. They were so helpful, they helped me reschedule my booking for the Kumamoto car ferry the next day as we were to view dolphins the next morning.
Did I mention dolphins? Our package included a huge Japanese-Western room (i.e. 2 beds, plus tatami space for dining/futons), a booking to use one of their exclusive baths (in the attached bathhouse next to the hotel), and a cruise to view the dolphins out in Shimabara bay on their own hotel ferry! At 22000 yen per adult and 7800 yen per child, this is superb value.
The hotel's own baths (free for guests) are nothing spectacular, but feature indoor and outdoor bathing with an expansive sea view. Awesome! There are even rooms with private baths, if you can afford them. The bathhouse' bath was booked for my family's exclusive use, and featured a family size indoor bath and a rather hot outdoor bath. But with the cold autumn winds, it was a wonderful experience.
Dinner featured the best of Amakusa's seafood. Live abalone steamed in a clay dish with parsley butter, live prawn sashimi (yes, the prawn was alive!), matsutake chawanmushi, grilled local chicken, sea bream kamameshi... Gorgeous!
Breakfast was buffet-style served in the dining room on the 1st floor. It had a decent selection of both Japanese and Western breakfast options. Nothing incredibly spectacular here, but delicious, well-prepared and served with a smile.
The dolphin cruise was wonderful and should be on the itinerary of all who manage to make their way to this part of Amakusa. You can get really up-close-and-personal with the various pods who make their home in Shimabara Bay, and they are generally unafraid of the human hordes trying to get a closeup shot of them swimming and diving. It's a 30 minute journey to and fro the dolphins' territorial waters, and the boat will linger for about 20 minutes there. According to the guide (who speaks some English), the chances of spotting dolphins is nearly 90% on any given day.