A KK (Kabushiki Kaisha) is the most popular form of corporation in Japan, and it should stipulate the term of office of directors (and auditors, if any) in the Articles of Incorporation. You can decide the term of directors from one year up to ten years, and once stipulated, you are requested to follow the rule.
Suppose you stipulate the directors' term of office as two years, the Articles of Incorporation usually have the following phrase:
Article XX The term of office of directors shall expire at the close of the ordinary general meeting of shareholders for the last business year that will end within two years after their election.To conform with this article, you are requested to biyearly elect directors at the ordinary general meeting of shareholders, and register it.
If you don't do this or filing is delayed, the representative of the company shall be punished by a non-penal fine. The amount of fine is usually around JPY100,000.