Ten Japanese Weapons Invented Too Late To Win World War II-- Part 1: I-401 Class Subs

From the February 16, 2016, Listverse by Sam Derwin.

10.   I-200 Class Submarines.  They could travel underwater faster than 20 knots while most submarines of the time couldn't do more than 10 knots.

9.  I-401 Class Submarine.  The largest ever constructed.  It was 60% larger than U.S. subs and could carry three aircraft.

8.  Kawanishi N1K1-J--  fighter plane

7.  Type 5 15-centimeter AA gun.  It could fire shots up to 65,000 feet and could easily reach our B-29s who were bombing Japan.

6.  Ki-83--  twin engine long-range fighter

Too Late, Too Little.  -GreGen