We have seen a lot of Japan-based OEMs launch Windows 10 Mobile in the last few months. The latest to do so is Cathay, which is releasing the ARP XC01Q phone later in April for business and commercial customers.
The Japanese press release says that the XC01Q comes with a Qualcomm Snapdragon 410 processor running at 1.2GHz, along with 2GB of RAM and 32GB of onboard storage, with a microSD slot that can support up to 64GB of additional storage. It also has a 13MP rear camera and a 5MP front-facing camera, along with a 2600mAhz battery.
Pricing was not revealed in the press release, but unless you live in Japan, it's unlikely you will get your hands on one.
Thanks to Akash for the tip!