Yagoro-don Festival held on November 3 every year serves as an annual autumn festival of Iwagawa Hachiman Shrine in Oshumi Town in Soo City, Kagoshima Prefecture. It is a gallant festival that represents the southern part of Kyushu and counted as one of the three largest festivals in Kagoshima Prefecture.

The highlight of the festival is the Hamakudari parade of Yagoro-don, a 4.85 meter tall giant with goggle eyes and strong eyebrows. Wearying long and short swords on his waist, the giant goes through the town in hope of a rich harvest. There are many theories about its origin. Some say that he is modeled after Takenouchi Sukune, a legendary hero who served six generations of the emperors. Others say that he was the head of the Hayato clan, who ruled the ancient Kyushu. It is believed that if you touch things pertaining to Yagoro-don, you will be in sound health for one year.

Toshihira Osumi was born in 1932, in Ota, Gunma Prefecture. His real name is Sadao Osumi. He was designated a Living National Treasure for his 'to-kaji' technique.

In 1952, Osumi became apprenticed to Akihira Miyairi (another Living National Treasure) and studied the craft of katana swordmaking. When he was 28, Osumi became independent.

He energetically entered competitions held by the Japanese Fine-Art Sword Preservation Association. In the first two competitions, he won a prize for effort. But from the 3rd to 8th competitions, he won a special prize. Finally, on the 10th, 12th and 14th times, he won the Manamune prize, which is the highest prize of all. Despite winning many prizes, Osumi is not proud. He believes that the implications of craftsmen are deliberated through their pieces.

In 2001, Osumi presented an amulet sword to Princess Aiko, the Princess Toshi. Moreover, he has dedicated many other pieces to places like Ise Shrine and Ota District.