Yaita Kinbei served as a blacksmith during the Sengoku period, manufacturing swords and, later, arquebuses modeled after a Portuguese model provided by Tanegashima Tokitaka.
Kinbei was born in Seki in Mino Province and moved to Tanegashima.
According to a historical account of the arquebus, in 1543, a Portuguese merchant aboard a Ming dynasty ship drifted ashore in Tanegashima. On this occasion, the foreign merchants introduced arquebuses to the Japanese for the first time. While witnessing a demonstration of the firearms, Tanegashima Tokitaka (who was sixteen years old at the time) was impressed at the power of the weapons and decided to purchase two of the arquebuses. He then brought one of them to Kinbei (Kiyosada) and ordered him to examine and produce more of the weapons while also ordering a retainer named Shinokawa Koshirō to research gunpowder. After great effort, Kinbei succeeded in manufacturing a Japanese version of the arquebus. The other arquebus was presented by the Shimazu clan to Ashikaga Yoshiharu, the twelfth shōgun of the Muromachi bakufu. Owing to its origins, the arquebus was also referred to as the Tanegashima firearm and brought revolutionary changes to the battlefield during the Sengoku period.
According to the genealogical records of the Yaita family, to learn the art of manufacturing arquebuses, Kinbei had his daughter, Wakasa, wed an individual from Portugal so he could learn the trade. This story regarding Wakasa is only in these records and through oral tradition. There are no references to this story in the historical account of the arquebus or records of the Portuguese. In 1545, Kinbei succeeded in his quest to manufacture the first arquebus in Japan.
The first arquebus manufactured by Kinbei is on display at the Tanegashima Development Center as a cultural asset of the city of Nishi-no-Omote in the northern part of Tanegashima. In the city of Nishi-no-Omote, there is a copper statue of Kinbei and marker at the place of his residence.