There is also another theory that this term originated from the purple color that was a symbolic color of the polar star because Kikko (hexagonal pattern) of tortoiseshell pattern used as a brand mark of Kikkoman Corporation was a symbol of the North Start belief (Myoken Bosatsu belief).
キッコーマンに代表される亀甲文様の亀甲は北極星信仰（妙見菩薩信仰）で、北極星のシンボルカラーである紫色からと言う説。