We added the following faq. (2017/11/16 update)
If in doubt, please see the following FAQs for help.
Rewards will be paid out for any confirmed vulnerabilities. The basic process for reward payment is as follows.
*1 Information Necessary for Payment
Personal information such as address, phone number, bank and bank account information will be taken from the Application Form for Income
Tax Convention or other related documents for bank transfer or foreign remittance purposes.
*2 Application Form for Income Tax Convention
Tax conventions are treaties established between Japan (source of the income) and the country where the individual resides in order to avoid
double taxation. Corporations and individuals residing in countries that have established tax conventions with Japan can avoid double taxation
for income earned from their reward in Japan (source of the income).
If a tax convention treaty has been established between your country of residence and Japan, the tax conventions are applied by submitting
two signed original "Application Form for Income Tax Convention" documents to LINE Security Bug Bounty Program. You may be able to
receive a reduction or exemption for any income tax withheld in Japan.