Satsuma Oku Motoyasu (薩摩奥元安) was born in 1758, he was named Oku Jirō ́emon (奥次郎右衛門) at birth. He was third son of Oku Motonao (元直) and younger brother of Motohira (元平) and Mototake (元武). Motohira was one of the best and famous Satsuma smiths and he worked in the Sōshū-Den. Motoyasu’s period of the artistic activity span years between Tenmei (天明, 1781-1789) and Bunsei (文政, 1818-1830) eras. Generally accepted that Motoyasu’s year of death is unknown. Lacking in this information looks very strange as the most smith from Shinshintō period are well documented. An example is the fact that the years of life of his older brothers are well known: Motohira (31.10.1744-13.07.1826) and Mototake (1748-1816). In our attempts to guess the years of Motoyasu’s life, we must proceed from his estimated date of birth in 1758 and from the last known dating of his works: the 4th year of the Bunsei era (文政,1821). We can find only an additional piece of information in Meikan that Motoyasu was great-grandson in 6th generation after Tadakiyo (忠清), who was founder and predecessor of Oku School of swordsmithing art named after his family name.
Motoyasu’s level of workmanship was very high and it is said that he was to his brother Motohira. At the same time, there is a lot of evidence that Motoyasu worked as an assistant to his brother, who at that time was a more famous and successful master producing gassaku and daimei swords. Motohira became the head of the Oku family in 11th of July, 1777, a little later in 1785 he received the right to sign his swords using the prefix «Sappan-shi» (薩藩臣, retainer of the Satsuma fief) and finally in the 1st of December, 1789 he received the honorary title Yamato no Kami (大和守). The close cooperation of the brothers is confirmed by the existence of a swords that was forged together, as evidenced by the following inscription made on the tang:
«Oku Yamato no Kami Taira Ason Motohira made this in cooperation with younger brother Motoyasu» (奥大和守朝臣元平与弟元安造之). This inscription one can find for example on the nakago of Jūyō Tōken #15, dated «on the 26th of December, 1799».
Figure 1. Jūyō Tōken #15.
It is one of the most rare example of so-called gassaku (合作) work: sword which was forged in collaboration of two or more smith (father and son; teacher and disciple or smiths connected by mutual lineage).
Figure 2. Another interesting example of the sword forged by Motoyasu. Signed: Satsuyō-shi Oku Jirō ́emon Taira Motoyasu (薩陽士奥次郎右衛門平元安); made on the order of Itō Den ́emon Fujiwara Sukenao (伊藤伝右衛門藤原祐尚応望); dated: on a lucky day of the 8th month of 1808. Dai Token Ichi Catalogue 2009, p. 134.