Information on how to obtain tickets to the Japanese premiere of Half-Blood Prince on July 6th, and early screenings thereafter, is now available. The premiere will take place in Tokyo, with subsequent screenings at Osaka on July 7th, Sapporo on July 8th, Nagoya on July 8th and Hukuoka on July 8th.

Venues, times and ticket prices can be found at the source.

Source: Potter Mania

UPDATE: Tickets cannot be purchased for this premiere and subsequent screenings, all tickets must be won.