I am a Nepalese currently living in Kyoto, business visa holder of Japan.

You should first prepare the required documents for HK tourist entry permit: copy of your passport, the application form, a passport-style photo, proof of your financial support, flight itinerary, hotel reservation and your travel plan. Afterwards, post your application to HK immigration department to apply for tourist entry permit. Here is the postal address:
Receipt and Despatch Sub-unit
HK Immigration Department
2/F, Immigration Tower
7 Gloucester Road
Wan Chai, HK