Madosma is a Windows Phone that is currently being sold by Mouse Computer Japan. Today, the company made an announcement that their smartphone will be getting the official Windows 10 Mobile upgrade on December 4 2015.
There are two ways to obtain it, one via the free OTA upgrade in December and another through service center which will be charging 3000 Japanese yen ($24).
You can read the review of Madosma here and its hands on pictures here. Main specifications include Qualcomm Snapdragon 410 (1.2GHz, quad-core) processor, 1GB memory, 8GB storage, 5-inch HD (1,280 × 720 pixel) IPS LCD display, 8 mega pixel rear camera and 2 mega pixel front camera.
Interface selection include Micro USB, micro SDXC card slot, Micro SIM, 4G LTE / Cat 4 (band 1/3/19), IEEE 802.11b / g / n-enabled wireless LAN, Bluetooth 4.0. Battery with capacity of 2,300mAh. Madosma windows mobile phone measures 70.4 × 142.8 × 8.4mm (width × depth × height) and weighs about 125 grams.