, better known as , was a Japanese samurai, master of hà Âjutsu, and scholar of kokugaku. He established the of gunnery.
Sakamoto Tenzan was born the eldest son of , a retainer of the Naità  clan and master of the of gunnery.
In 1767, when he was 22 years old, Sakamoto traveled to Osaka to study under the instruction of .
In 1778, Sakamoto published an advanced design for a portable swivel gun called a . He explained the gun using concepts from the Yijing.
In his later years, Sakamoto investigated measures for erosion and flood control. Earning the ire of his colleagues, he was ordered into house arrest for several years before being released. He died in 1803.
Sakamoto's grandson, , defended Osaka Castle from à Âshio Heihachirà Â's army of revolt in 1837. His granddaughter, , was the stepmother of Shimazaki Masaki, father of noted author Shimazaki Tà Âson.