There will be NO registration fee for the meeting.
Accommodation should be booked individually by the participants. Hotel prices vary between about 50 and 250 EUR/night. Most hotels are in central Kumamoto (ca. 3 km-s from Kumamoto Univerity, the conference venue). Toyoko Inn in the centre, for instance, is a reasonable choice — provided they have vacancies (you can book with them 3 months in advance, on their own website). (You might try ‘Airbnb’, that is becoming popular in Japan, too.)
Meals (lunches, dinners) will not be organised, either (apart from perhaps a banquet event). The cafeteria on the South Campus (called ‘FORICO’) will easily accommodate all participants and offers resonable food at reasonable prices (1000 yen, less than 10 EUR, is more than enough for a meal). Restaurants, particularly in the city centre, can be found in great numbers.