A deposit bonus is an offer that casino players get once they deposit funds on their player accounts. Casinos use deposit bonuses to attract players to their sites and encourage them to make deposits. The logic behind deposits bonuses is that an extra cash prize will encourage further deposits to the account.
When mentioning Japan, people often think about sushi and samurai, but the Japanese are also famous for being hardworking and humble. Most forms of gambling are banned in Japan, but online mobile gambling is growing fast in the country and it's easy to find attractive bonus offers targeting Japanese residents.