Submarine 707R

In a bid to maintain peace across the oceans, the multinational organization PKN was established, bringing together cutting-edge battleships from various nations. During their inaugural ceremony, however, a mysterious group known as USR launched a surprise attack, aiming to seize control of the world with their formidable submarine, the UX, commanded by Admiral Red. Just when all seemed lost, the aging Japanese submarine, 707, under the command of Captain Hayami, intervened heroically, turning the tide at great personal risk.

One year later, the legacy of the original 707 continues with its successor, the advanced submarine 707 II, embarking on its maiden voyage. Among the crew are young trainees Kenji, Goro, and Senta, as PKN assembles a fleet led by the formidable Great Guardian, the latest American battleship. However, the fleet faces relentless assaults from the enigmatic Submarine U, leading to catastrophic losses. As the situation deteriorates, the 707 re-emerges, prompting a fierce confrontation between Captain Hayami and Admiral Red. In a desperate bid to escape a devastating trap, the 707 finds itself in peril, caught within a treacherous crater while enemy torpedoes rain down.