Do I need a transit visa for Hong Kong if i am going to Japan on Cathy Pacific Airline? I have a Japan visa.
You need a transit visa. From the HKSAR IMMD website:
All nationals (except holders of Diplomatic and Official passports) are required to hold a valid visa for the HKSAR for whatever purpose (including those who are in transit and remain on the airside). Holders of Diplomatic and Official passports may visit the HKSAR visa-free for a stay not exceeding 14 days.
You may apply to the Chinese diplomatic post in Pakistan closest to your place of residence, or to the Hong Kong SAR Immmigration Department directly (by post). See this page for details.
You may as well cancel a ticket and transit through mainland China or Taiwan instead, where you can transit without visa (TWOV) as long as you stay within the designated transit area.