Mondo no Sho Masakiyo was born in 10 (1670) in Izumi-go of Satsuma Province and studied swordmaking under Maruta Sozaemon Masafusa, a smith in the service of the Satsuma domain. He initially signed his work Kiyomitsu, later changing to Masakiyo. In the first month of Kyoho 6 (1721), together with Ippei Yasushiro, he was summoned by the eighth shogun Tokugawa Yoshimune to forge in . His skill was acknowledged, and the bakufu granted him permission to cut the ichiyo- crest on the tang; on his return journey he was appointed Mondo no Sho by the Imperial Court. He died in Kyoho 15 (1730) at the age of sixty-one. Together with Yasushiro, he stands as "one of the twin pinnacles of Satsuma ." In his later years, many works are encountered that were signed as by his son Masachika and his student Masamori.
The consistently describes Masakiyo's signature idiom as a -like rich in variation. The is typically mixed with , , and ; the is deep and the adheres thickly, characteristically with "somewhat coarse " producing an unevenness that distinguishes his work. Long , , and run vigorously, and -like effects at the crests of the temper produce a -like appearance that "conveys an impression of antique flavor." The consistently displays vigorous with long . The shows mixed with and , tightly forged with thickly applied and abundant ; the steel often assumes "a somewhat blackish tone." Where Yasushiro "often tempered calm, -based ," Masakiyo's -style approach yields that is "bright and clear" with activities "especially prominent toward the crests of the temper pattern." The finest works display an - mode and, at times, a "lively " with and sanjuba-like effects that intentionally evoke the manner of Masamune.
Masakiyo is praised as "particularly adept in the -," with works "so accomplished that they may at times be mistaken for upper-ranking ." The example -- with its extremely wide , thick , and richly fleshed form -- is described as creating "an especially grand and heroic presence" and "the feeling of a decisive downward cut," earning recognition as "a masterpiece of Mondo no Sho Masakiyo, exhibiting outstanding excellence among his works." Historical documentation further elevates his standing: the blade was presented by the Satsuma domain lord Shimazu Tsuguhisa to Konoe Iehisa, Left Minister, who "took exceptional pleasure" in it and bestowed upon both Masakiyo and Yasushiro gifts of fine silver and poems from the Six Immortal Poets.