I am playing as the Tokugawa right now and the Teppo Ninja seem to only require a criminal syndicate to be recruited even though they are a gunpowder unit. Is this supposed to be that way? It seems like an incredible fast way to get to gunpowder units.

Teppo Ninja only needing the criminal syndicate is intended. I could slap the generic "gunpowder mastery" tech on them like for all other gunpowder units but personally dislike these harsh requirements. The only thing that it achieves is locking units away for most of a campaign and when recruited are just a trophy unit. Another point is that I want some niche arts like "school of shinobi" to be at least situationally useful for certain clans. Also, I rarely invest much research in the "way of chi" especially the middle section of it due to better/more important military arts.

Nagamaki Sõhei has the same charge bonus as veteran no-dachi samurai, and only 3 of melee defense. As far as I know, the thing with the nagamaki is that it can be used as a naginata as well as a katana, so I think the stats of that units should be an intermediate between naginata and katana Sõhei.

Thanks for reporting that. I will change the values of "Nagamaki Sõhei" & "veteran no-dachi samurai" so there is a real stat progression. As already replied in your other post I found no real/significant difference between Nodachi (Ōdachi) and Nagamaki usage during my very brief research on that topic. To my understanding the main difference is the hilt length with Nodachi/Ōdachi having the shortes, Nagamaki are intermediate and Naginata being the longest one.

Thanks for the dedication. My research was probably shorter than yours, but I think the nagamaki has a handle the same length as the blade, while these units has a 60-40% handle/blade. If it's not a big deal, I think you could fix that by removing a little piece of the handle and keeping the blade. The animations won't get weird. I loved the units anyway, thanks for that.

As far as I can tell your right with the 50/50 ratio of handle / blade for a nagamaki. Sadly I can't edit these models because first they aren't mine, the original mod owner is Engineer Weierstrass (MoSS dev), and second I don't own the required 3ds Max.

Edit:
Nagamaki stats have been patched as of 18.04