見聞諸家紋 (Kenmon Shokamon)

見聞諸家紋, c. 1467–1470 (also 東山殿御紋帳). Muromachi album of warrior-house drawings; type-names on surviving copies are later labels, not original Muromachi captions. (National Diet Library (later transcript))

Supports: Historian pass shows uroko-tomoe in Kenmon, not a labeled Hōjō three-triangle pile. Does not by itself document this 1272 flag type.

北条氏過所船旗 (Hōjō kasho-senki, Bun’ei 9 / 1272)

北条氏過所船旗 (kasho-senki), Bun’ei 9 (1272). Kyoto University Museum; Important Cultural Property. Hōjō tokusō three-triangle charge on a maritime transit flag. (Kyoto University Museum)

Supports: Supports the specified 1272 Hōjō tokusō three-triangle ship-flag type. Does not license recutting medieval long-base isosceles triangles into later printed equilateral 1-over-2 piles, and does not bundle Kamakura Hōjō with Go-Hōjō of Odawara.

三鱗文兵庫鎖太刀（号北条太刀） (TNM/ColBase F-151)

三鱗文兵庫鎖太刀（号北条太刀）, 13th century. Tokyo National Museum, ColBase F-151. Three-scale marks on the koshirae; later Odawara-Hōjō donation tradition. (Tokyo National Museum)

Supports: Supports a 13th-century three-triangle mark on the ‘Hōjō tachi’ koshirae. The Odawara-Hōjō donation is later tradition, not a reason to recut the triangles into Edo equilateral geometry.

太平記 (Taiheiki)

太平記. Later medieval war tale including the Enoshima dragon-scale legend attached to Hōjō.

Supports: Named only as a fence: the Enoshima legend is not an origin for this 1272 flag type.