In the silent depths of the Pacific, where Japan's sensuikan—the I-boats of the Imperial Navy—stalked Allied convoys, a new weapon turned the tide of war. TEKI KUCHIKUKAN, TANCHI! ENEMY DESTROYER, DETECTED! tells the gripping story of the Hedgehog, a British-designed anti-submarine device that armed U.S. ships with devastating precision. From the USS England's six kills in twelve days to the USS Batfish's triple sinking in 1944, this revolutionary weapon crushed Japan's submarine fleet, securing the supply lines that fueled the Allied victories at Iwo Jima and Okinawa.

Drawing on naval archives, survivor accounts, and the voices of Japanese and American sailors, this book unveils the human cost of a hidden war. The cry of "Teki kuchikukan, tanchi!" marked moments of terror for submariners facing the Hedgehog's silent, lethal strike. This meticulously researched narrative explores the strategy, technology, and sacrifice that defined the Pacific War's underwater campaign, revealing how a single weapon forged a silent victory that changed the course of history.