The Sakai family was one of the oldest following families of Tokugawa and its origin was Sakai village in Mikawa province. The Sakai family was divided to two families, Saemonnojyo and Utanokami. It became to follow the Matsudaira family in Mikawa province, and also became the server of Ieyasu. After the Tokugawa shogunate government was founded, the family of Utanokami Sakai would become the server of Shogun and played the important role of government.
The Sakai family in Obama Han started with the third son, Tadatoshi, of Masachika. He was belonging to Utanokami family and became the server of Ieyasu. He was given 3000 Koku to Kawagoe in Musashi province in Tensho 18(1590), he was given 10000 Koku to Tanaka in Suruga province, again gone back to Kawagoe and given 37000 Koku in Genna 5(1619) and became the Oorusuiyaku of Edo castle and Toshiyori.
Tadatoshi's son, Tadakatsu, also followed Ieyasu with Tadatoshi and was given 3000 Koku to Shimofusa at first. After the Tadatoshi's death, he would come back to Kawagoe, then was moved to Obama Han and became the first feudal lord of Obama han in Kanei 11(1634).
This armour was actually used by Tadatoshi and there is a word of Dragon on headpiece. The headpiece has the black stand of Ichinodani on Hinenozunari. Iyozanekiritsuki iron plates were used for the body part. There are Fukubegote, Eccyuhaidate and Eccyusuneate with the armour. It is simple armour which was common in the Warring States period.
Even though it was made for actual war, it has brilliant decorations which show the trend. There are family crests of Sakai in Tekkou and Haidate and also some scars of fighting.
Explanation 
Obama city
