JAL operates extensive and frequent domestic services throughout Japan. But Japan Air Lines also offers a wide range of destinations throughout the Far East and Southeast Asia, as well as to the USA and Europe.
For the best deals, book your tickets with JAL at least 1 month before departure, but no more than 4 months. Since JAL does not operate any direct service to the Czech Republic or surrounding areas, you will encounter them rather sporadically when combining with another airline.