1. Not good torpedo bomber. High wing loading (developed as unarmed extreme light recon plane) without armour protection.
Kankoh (B5N) and Tenzan (B6N) also had no armor
2. Add to this almost zero capability for self-defense (and even forgot about strafing when attacking)
Mosquito says: speed is the best defence, especially if you are faster than a hellcat
*but i agree, putting a short barrel Type-99 20mm for the rear gunner would be appropriate,
in fact it should have been done on all japanese planes, those 7.7mm guns are useless against F6F armor
3. Just dont needed plane for Japan when it ready.
Would have been ready by early 1944 if it were a priority
Yes this plane can carry torpedo. But it overload this plane critically. Main thing for TB it ability for mantain attack course under attacks of figthers and flak fire. That need compromiss between wing load and protection. This plane dont have both. If you want use TB with lowest durability (if devs add this TB to game) than Ok. But in really this plane on low altitude just fragile, non-defended and sluggish fuel cistern. What good on 6000m alt not always good on 100m
Still think you are confused about wing loading and wing stress, P-47 has the highest wing loading of any fighter but it's as stable as a rock
Saiun engine was a 1-stage-2-speed Ha-45 for medium-low altitude, not a 3-stage Ha-32-25 or Ha-45-ru
still is amazing to me.. after the first message broadcast from a Saiun *no Grummans can catch us*, it was never fitted with torpedoes
an excellent design with laminar flow wings and a powerful engine - Myrt and the Dinah are two underrated japanese designs
"No Enemy Survives Contact with the Plan" - Commander Stormwolf