The Heianjō school (平安城) of swordsmiths represents the principal lineage of Kyōto sword production during the period. "Heianjō" is the classical name for Kyōto (-kyō), and the school's smiths — resident in the district of the capital — signed variously with the 平安城 (Heianjō) and 三条 () prefixes, a usage that has often caused them to be confused with the far earlier school of Munechika. They are an entirely distinct, late group: its two representative masters, Heianjō Nagayoshi (平安城長吉, also read Chōkichi) and Yoshinori (三条吉則, of the Fuse 布施 family), are counted as the leading makers of -period Kyō-mono (Kyoto-made blades), carrying forward the capital's swordmaking after the -period and Hasebe lineages. Both names continued through several generations from the late era into the sixteenth century, and the smiths are known to have travelled to forge (desaku) in provinces such as Izumi, , and during the late period.
The Heianjō style is dominated by a flamboyant (full-temper) idiom adopted from tradition: a foundation of large mixed with , , and , with abundant and spreading temper across the entire blade surface, adhering strongly, and and coursing through a bright, clear . The finest examples are so accomplished that they are difficult to distinguish from late (Sue-Sōshū) work. A quieter - and -based mode close to the tradition is also seen. High-quality — , , , and — frequently accompany the blades. The school is not to be confused with the unrelated Heianjō- (平安城象嵌) inlay tradition of tōsōgu makers.