Before the forge
He was born in 1984 in Nantan, in the Tanba region. As a child he was struck by a sword he saw at the Kyoto National Museum. After finishing high school he worked in a car factory, in Mie prefecture, to save money, and at twenty he became the apprentice of a swordsmith in Fukushima.
With Fujiyasu Masahira
His master was Fujiyasu Masahira (藤安将平). He trained with him for seven years and set up on his own after the Great Tōhoku Earthquake, in 2011. His master gave him the character 将 (masa) from his own signature, 将平 (Masahira), and he signs 将大 (Masahiro). Two sources place the master in the city of Fukushima; another says that he trained with a master from 磐州 (Banshū), the old name of the Iwaki region, also in Fukushima prefecture.
The Kameoka workshop
In October 2014 he opened the 将大鍛刀場 (Masahiro Tantōjō) in Kameoka, in Kyoto prefecture. It took him some two and a half years to fit it out, and to pay for it he worked as a removal man. He is held to be the only swordsmith in Kyoto prefecture; in the whole of Japan there are fewer than three hundred.
The workshop
The entrance of the 将大鍛刀場 (Masahiro Tantōjō), in Kameoka. Photo: dealer in Japan 
Inside the workshop: the power hammer and the hearth. Photo: dealer in Japan 
At the hearth. Photo: dealer in Japan 
A visit to the workshop. Photo: dealer in Japan