This is silly.

The Japanese in this case we're talking about is 16th century.

The Roman army in question is 2-3rd century.

No matter what you look at the Romans are clearly outclassed here in terms of fighting techniques, technology, etc. I mean of course the samurai equipment will be superior to anything an Imperial Legionare carries.

Even if we're to take the Byzantine Empire it's peak was about 12-14th century and they evolved from how the Romans fight at that time.

For arguments sake and for the thread

A typical Roman army would consist of legions plus auxilary units from whatever local region is possible. The vast majority will of course be of the heavy infantry type which carries pilum, shield, and gladius. And again, Roman legions fight as a single unit and not individually. Whereas a gallic army could bring in 2-3 warriors to a front line a Roman army could bring in 5-6 guys to a front line. Roman armies are deadly in close quarter combats because the gladius does not need a lot of space to fight in. Plus the Legionaries would have tons of experience from fighting the dozens of various tribes they've had over the years. Add to the fact that they are professional soldiers as well and are extremely disciplined.

Then you add in their auxillary units which could include light infantry or cavalry for support.

A japanese army I do not know much but I'm pretty sure that the majority of them would be ashigaru soldiers whose equipment aren't as good as a samurai's which make up a small core.

So really the Roman army wouldn't exactly be facing 10,000 samurai would they?