Yes, it's Gundam, right? (Wrong)
This is the MG Musha Gundam Mk-II Tokugawa Ieyasu Nanban-style armor ver., which I bought when I went to Nikko Toshogu Shrine during Golden Week.
There was plenty of stock available, so you could easily buy it if you went there.
The photo shows it without the Nanban-style armor, but with the horned helmet, which was an extra part.
Musha Gundam is so cool, I think I'm going to get hooked on this series...!

Speaking of Nikko Toshogu Shrine | ハル's Gunpla works