Sanchōmō, or Yamatorige, is a legendary 13th-century Kamakura period tachi sword designated a National Treasure of Japan. Historically associated with the Uesugi clan and wielded by Uesugi Kagekatsu, its name evokes the flamboyant temper line resembling a copper pheasant's plumage or sunset mountains. The blade measures approximately 78.3 cm, featuring deep curvature, a distinctive ikubi-kissaki tip, and aikuchi-style koshirae without a tsuba.

In the anime *Toku Touken Ranbu: Hanamaru ~Setsugetsuka~*, Sanchōmō manifests as the sword spirit Yamanbagiri Chougi. As the original "master copy" of the renowned Yamanbagiri, Chougi displays a provocative, confrontational demeanor towards Yamanbagiri Kunihiro, his reproduction. This dynamic fuels interpersonal tension within the citadel, especially during the "Yuki no Maki" (Chapter of Snow) storyline. Chougi arrives during a critical mission to investigate a history-altered Bakumatsu-era Tosa (1863), joining efforts to restore the timeline alongside other sword warriors.

Chougi's interactions reveal his complex perspective on identity and legacy, contrasting Kunihiro's internal struggles as a replica. His role extends beyond interpersonal conflict, contributing to the unit's objectives against historical distortions. The blade's real-world significance as a cultural artifact—purchased for 500 million yen in 2020 and housed in the Bizen Osafune Japanese Sword Museum—echoes its narrative weight within the anime.