Considering the missile threat from North Korea you would think Japan would have begun doing strategic decision making about fielding a robust missile defense system years ago:

Japan’s military is considering developing a missile shield defense system to protect against a North Korean rocket launch.

During his visit to China, Japan’s Defense Minister Yasukazu Hamada told reporters that he was mulling how to issue an order to mobilize a missile shield in accordance with Japan’s law on its Self Defense Forces.

Japanese media then reported that Tokyo is likely to issue the order after a related ministerial meeting before the end of this month.

Meanwhile, speaking before the parliamentary budget committee, Japanese Prime Minister Taro Aso said Japanese intelligence believes North Korea will likely launch a rocket on April fourth.  [KBS Global]

If the Japanese are looking for a system to compliment their AEGIS SM-3 interceptors then I have a candidate system for them.