You can get in contact with the institution calling the following number (+66) 5320-3367 or visit the Consulate at 104-107 Airport Business Park, 90 Mahidol Road, Haiya, Muang District, Chiang Mai 50100, Thailand yourself. If you want to omit the visit to the Embassy, simply apply for a Japan e-Visa online. Fill the application form within minutes from home.
Visa to JapanJapan Electronic Travel Authorization