so i was playing total war shogun 2 and i realized something after about 50 hours of gameplay. none of the units have shields and as it tuns out japanese dident use shields for some reason ? what was the reason ?
If you're referring to hand-held shields, known as tedate, they were common up until the early-Heian period. Samurais in Shogunate Japan didn't use them as much as before, but they were still around.
Apart from this, standing shields called tate were used. They were effectively used as shield walls by placing them in lines, providing cover for archers and arquebusiers.
In the late-Heian period, as well as Kamakura period and Muromachi period, horse archers were the backbone of the military force and they didn't have use for hand-held shields. Instead, they adopted ō-sode, a shoulder guard, which was considered a pseudo-shield.
Tate shields were around up until the Edo period and saw transition in their designs throughout the years leading up to it.
In the later Edo period, smaller tedate made of metal were still being used by warriors mostly to defend against pistol shots.
So the idea that Japanese didn't use shields is faulty, although it's true that shields were not that much of a popular armour.
Sources:
Samurai Armour: Vol I; The Japanese Cuirass by Trevor Absolon
Heavenly Warriors: The Evolution of Japan's Military, 500-1300 by William Wayne Farris
Well historically a lot of early japanese warfare was based on archery and more specific cavalry archery, in which shields were not effective to carry.And when it comes to infantry, katanas are mainly two handed weapons plus their well build armor protected them a good bit against arrows and the like.
Hope this answers the question and if you want a more detailed answer I linked you a old sub which goes a lot more into detail.
https://www.reddit.com/r/AskHistorians/comments/x8rtx/why_didnt_the_samurai_use_shields/