Carbon-Ion Radiotherapy facility called “i-ROCK” (ion-beam Radiation Oncology Center in Kanagawa) started the clinical operation in December 2015 in the city of Yokohama, Kanagawa prefecture. Being close from Tokyo Haneda airport, it is conveniently located for visitors from overseas. “i-ROCK” being along with the special hospital for cancer provides carbon-ion radiotherapy in cooperation with specialists of various types of cancer.