Kimura Matazō served as a bushō from the Sengoku to early Edo periods.  Matazō was a retainer of Katō Kiyomasa (a daimyō and the first lord of the Kumamoto domain in Higo Province).  Matazō is counted among the Sixteen Generals of the Katō – a group of sixteen elite retainers of Kiyomasa.

More so than his actual circumstances, he gained notoriety in the Edo period through storytelling.  As a result, the line between historical fact and legend is unclear.  He was regarded as an accomplished sumō wrestler and his bout against Keyamura Rokusuke (Kida Magobei) is well known.

Matazō originated from the Ōmi-Kimura clan, members of the Sasaki clan who were descendants of Emperor Uda from the Heian period in the late ninth century.  The Kimura came from the village of Kimura in the Gamō District of Ōmi.  He was born as the son of Kimura Mataemon Harumasa, a lieutenant-general under the command of Rokkaku Jōtei (Rokkaku Yoshikata) descended from the same Sasaki clan.

One day, Matazō was serving as an attendant at a banquet when Jōtei was almost assassinated by Sunamura Dairoku (a retainer of the Asakura clan named Yagumazō Kagetaka).  Matazō fled and was later found shaking in a closet.  Owing to this incident, he was called Matazō the Coward.  According to one legend, he was embarrassed by the moniker so paid a visit to the Kitamuki-Hachiman Shrine whereby, under the divine protection of Hachiman-Daibōsatsu (a Shintō god), he acquired great power and unrivaled valor with enough strength to toss a wild bull.

His father, Harumasa, was killed during the Siege of Kannonji Castle on 9/12 of Eiroku 11 (1568), after which Matazō became a rōnin, or wandering samurai.  Acting on his own accord, he participated in the Battle of Anegawa, killing a heroic retainer of the Asakura named Amijima Zuitenbō.  During this event, Matazō served as a retainer of Katō Toranosuke (Katō Kiyomasa) who was relatively unknown at the time.  Thereafter, together with Iida Naokage and Inoue Daikurō, he fought in numerous battles in support of Kiyomasa.  After Kiyomasa received a fief of 170 koku, Matazō was specially treated with a grant of 100 koku from out of the 170 koku.

In 1583, at the Battle of Shizugatake, Kiyomasa killed an enemy commander, Yamaji Masakuni.  After the battle, he was recognized by Hashiba Hideyoshi as one of the key contributors, referred to collectively as the Seven Spears of Shizugatake, and received landholdings of 5,000 koku.  Matazō and Daikurō each received a fief of 1,000 koku.  In 1586, after Kiyomasa became a daimyō with a fief of 250,000 koku in Higo Province, Matazō, Naokage, and Daikurō each received a fief of 10,000 koku, ranking at the level of daimyō.  Nevertheless, Matazō returned his stipend and chose instead to travel through several provinces, fighting against assorted characters ranging from local heroes to ninja.  A while later, he returned to the Katō family and, for the remainder of his life, devoted himself to Kiyomasa as he served with dedication for the Toyotomi family.  In accordance with the last will of Kiyomasa, Matazō left the Katō family, entered Ōsaka Castle, and joined in the Siege of Ōsaka.  Later, he returned and committed seppuku in front of Kiyomasa’s grave in Higo.