Japanese torpedos were sure a lot better than ours in WWII. Very glad that their submarine tactics sucked.
Long Lance, I believe that they were called.
The Japanese strategy was that only capital ships were worthy targets. Merchant ships were to be left alone and possibly a sign of cowardice to attack one. Later, they decided to turn subs into delivery vehicles.
The long lance did most of it’s damage from the ship launched ones. Had a range of 20,000 yards I believe.