This is a submarine action story that actually respects the submarine. Not anime submarines with inexplicable physics, but tactics, depth, sonar, the weight of command decisions in a tin can under pressure. Two episodes means no bloat, no filler, no time spent on anything except the next mission and the next threat. If you want naval action stripped down to its core, with hardware that matters as much as the crew, this is built for you.
A year after a devastating attack on the newly formed PKN naval alliance, the world's oceans remain under threat. The mysterious USR organization continues to hunt for dominance, wielding the formidable submarine UX as their weapon of terror. Standing against them is the 707 II, a cutting-edge Japanese submarine crewed by experienced officers and eager young trainees: Kenji, Goro, and Senta. As the PKN fleet mobilizes with their flagship, the Great Guardian, tensions rise between nations and uncertainty spreads across the seas. The 707 II must navigate treacherous waters where every sonar ping could mean the difference between victory and annihilation. The young trainees face their first real test, discovering that theoretical training means nothing when enemy torpedoes are streaking toward your hull. This is submarine warfare stripped to its essentials: tension, strategy, and the claustrophobic horror of underwater combat. For viewers who crave tactical action sequences and the visceral thrills of naval combat, the 707 II's battles deliver high-stakes encounters that don't rely on supernatural powers or flashy effects.