Koka Era
弘化（こうか）
Kōka (1844–1848) was an era falling between Tenpō and Kaei. Minamoto Kiyomaro (1813–1854), the shinshintō smith who led the revival of the Sōshū tradition, took the name "Kiyomaro" in Kōka 3 (1846), receiving the character "kiyo" (清) from his mentor and patron Kubota Sugane. Works produced after this renaming are regarded as belonging to Kiyomaro's mature period.
Description
Placing the Kōka Era
Kōka (1844–1848) was a late-Edo era after the Tenpō Reforms and before Kaei, as the Bakumatsu period drew closer. It is notable as the era in which Minamoto Kiyomaro, the shinshintō smith who led the Sōshū-tradition revival, reached his mature period.
From Youthful Training to His Move to Edo
Born the son of Yamaura Nobutomo, a rural samurai of the Komoro domain in Shinano Province, Kiyomaro studied at around 17, alongside his elder brother, under Kawamura Toshitaka, a smith retained by the Ueda domain. In Tenpō 5 (1834), backed by his future patron Kubota Sugane, he moved to Edo, initially signing as Yamaura Tamaki.
Mentorship Under Kubota Sugane and the Renaming to "Kiyomaro"
Kiyomaro's patron, Kubota Sugane, a military scholar of the shogunate's Kōbusho academy, recognized his talent and gave him lasting support. In Kōka 3 (1846), Kiyomaro is said to have taken the character "kiyo" (清) from Sugane's name, replacing his earlier signature "Masayuki" with "Kiyomaro" — linked to a blade he forged for Sugane, cited as testimony to their bond.
The "Yotsuya Masamune" and the Sōshū Revival
Kiyomaro's forge in Edo's Yotsuya district earned him the epithet "Yotsuya Masamune," after the Kamakura master Masamune, for a vigorous style modeled on Nanbokuchō-period Sōshū work. His blades are said to have later been favored by Kondō Isami of the Shinsengumi. His Kōka-era work, among roughly 130 blades forged in his lifetime, later captivated Bakumatsu-era activists.
Characteristics of This Era
- Kōka (1844–1848) was a late-Edo era between Tenpō and Kaei, as the Bakumatsu period approached
- The era in which Minamoto Kiyomaro, leader of the shinshintō Sōshū revival, reached his mature period
- In Kōka 3 (1846), Kiyomaro took the character "kiyo" from his mentor Kubota Sugane's name and began signing as "Kiyomaro"
- Established a vigorous, combat-ready style modeled on Nanbokuchō-period Sōshū work, rich in jigane activity
- Earned the epithet "Yotsuya Masamune," and is said to have later been favored by Kondō Isami of the Shinsengumi
- His Kōka-era work is considered representative of his mature period, holding an important place in shinshintō research