In the year 20XX, the state of world affairs is changing at a dizzying pace. This is particularly clear in the growing military strength of countries neighbouring Japan, the issue of resources on the sea floor, disaster relief, underwater transport, maintaining order on the high seas and island defence. In response to a near-skirmish with China over the much-disputed Senkaku Islands, Japan builds the aircraft carrier "Ibuki" and organises a new fleet...