The following story was copied for the Helena Organization Newsletter dtd October 2002.
Ysuyoshi Nagai was a pilot of a plane that torpedoed the USS Helena at Pearl Harbor.
Nagai was the commander of the 3rd Torpedo Attack Unit, Nakajima flying Kates B5N2 from the Japanese ship Soryu. They intended to hit the aircraft carriers they expected to find moored off the northwest part of Ford Island.
One of his flights made LT Hirata Matsamura angry when he torpedoed the target ship Utah.
Nagai left the lesser ships alongside Ford Island and looked for an alternative target. He selected the pared Oglala and Helena at Ten Ten pier. His torpedo passed under the shallow Oglala and struck the Helena
The latter suffered from the direct hit, but was not hit again and survived.
Oglala had a wooden hull which cracked and she capsized.
More can be found about the Japanese attack units in Osprey books, Campaign 62 Pearl Harbor 1941; Aircraft of the Aces 22 Japanese Navy aces 1937 - 45; Aircraft of the aces 13 Japanese Army aces 1937 - 45. For more on the internet, search for Osprey Publishing and there you can find real-time interactive military history area. The above is part of the essential Pearl Harbor.