Heike Tsuruginomaki

Passed down in top secret among the biwa hōshi—blind monks who played The Tale of the Heike on the biwa lute—the scroll is meant to take place in the eleventh book of the Tale, following the chapter "The Sacred Mirror Enters the Capital" (内侍所都入) and in place typically occupied by a short chapter similarly entitled "Swords" (剣).

[1] (This version of the text is believed to have a strong connection to Book V of the Gukanshō, which includes a passage describing Emperor Antoku as a transformed daughter of the Dragon King who had returned to her home beneath the sea.

[1]) The expanded scroll adds further anecdotes about the prized swords of the Minamoto lineage, their virtuous power, and their names, resulting in a much larger, 120-verse text that appears in two parts, the upper and the lower (つるぎのまき・上下).

[1] At the end of Part 2 of the Shōkōkan text is a reference to the inheritors of two swords being the houses of Nitta and Ashikaga, which led Yamada Yoshio to theorize that it was an addition made during the time of the rivalry between these two clans.

[1] Renaming it Usumidori (薄緑, "Pale Green"), by the power of this sword, Yoshitsune was able wipe out the Taira clan at the Battle of Dannoura.