Like Ko-Bizen tachi, the early Ichimonji blades were predominantly slender with strong koshi-zori and ko-kissaki and with a hamon of choji midare in ko-nioi and nie. The later, heavier blades, however, became much more exhuberant with the hamon extending high towards and sometimes into the shinogi.

The Ichimonji smiths were divided into four groups: Fukuoka, Yoshioka, Soshu and Katayama. The Kamakura smiths were a Fukuoka sub-group. The Fukuoka were the oldest and most prolific of the Ichimonji smiths. The earliest Fukuoka group was the Ko-Ichimonji school comprising Norimune, his son Sukemune and Narimune. Among the Fukuoka smiths were Norimune, Muneyoshi (his son-in-law), Sukemune (his son), Sukeyuki (his cousin), Yukikuni (Sukeyuki's son), Kanemichi, Sukezane, Yoshimoto, Yoshihira, Munetada, Yoshimochi, Sukefusa, Nobumasa, Sukenori, Sukenari, Kanemichi, Sanefusa, Yoshifusa, Tomosuke, Munetaka and Kanesuke. The Yoshioka school was founded by Sukemitsu and the Soshu school included Yoshiuji, Yoshitoshi, Yoshimori, Yoshisada and Yoshihisa. The Katayama school, founded by Fukuoka Nobufusa, settled in neighboring Bitchu.

Almost all of the smiths signed with a simple Ichi but there are variations in the way the single-stroke character was written. The Fukuoka character is slender with pronounced accentuation at the beginning and end. The Yoshioka character is very similar, but with less pronounced accentuation. The Soshu and Katayama characters exhibit no accentuation at the end. The Soshu was a moderate-length stroke of even width and the Katayama was of even width, but short and thick.