The nearest airport is Kagoshima airport, from which you can take an airport bus to JR Ibusuki station (95 mins, 2,400 JPY). The bus schedule can be found here (an English version is available here).
Shuttle service between JR Ibusuki station and the hotel will be provided. The shuttle will leave the station at 15:10, 16:25, 17:25 and it takes 10 mins. If this schedule does not work for you, please take a taxi or inform organizers your flight schedule in advance.
Another possibility is to take the high speed train Shinkansen to Kagoshima Chuo station and then take a local JR train to Ibusuki station. Shuttle service will be provided from JR ibusuki station as mentioned above.
Accommodation
Participants are expected to stay at Kyukamura Ibusuki. Please contact the organizers.