I KNOW there are big men with +5 better OD than the ones we are using but they are not even on the team.
Where?
This is list of all the best bigs out of NT roster:
Shibukji - allstar potential
Sonoda - faaaaaaaaar from OD 5+ ;-)
Wakatsuki - OD = 1
Motoori - quite good, however salary only 40k, too weak.
Kouzuki - yep, he has OD>=5. However he is 35yo, and every Friday he can drop by few levels.
Takizawa - OD = 1, allstar potential
Kishita - if trains can be good in future, now he has salary = 35k.
Suenami - great OD. 35yo, 36k.
All other bigs aren't even worth to say one word about them at this moment (of course few young players could be in NT in future).
In fact, there is only one big on NT level in Japan. It's Furusawa. And he was created in USA in NBBA team, then he played in Sharman. He is 31yo and in next cadency his skills will start to drop. There are few other bigs who are on U21 level. However he wouldn't be sure to play in U21 European Championships final.
So it means that in previous over than dozen seasons even ONE SINGLE good big Japan player weren't created.
However it's very easy. All is needed to play now in Japan NT is:
OD = 6
PS = 4
IS+ID+RB = 45.
And this player is sure to play in NT. Only 4 seasons training is needed.
In last draft was one good player - 18yo, MVP, OD=5, PS=6, TSP=45, 216cm. Quite good skills contribution, RB=1 isn't problem with this height, he should pop 3 times for every 4 RB trainings. He don't even need training out of position. However he was sold to Macau with price = 250k...
I can't help You if You don't want to help Yourself.