Some say the Chinese character '大' (dai) included in 大文字焼 (Daimonji-yaki) (Mt. Nyoigatake), bonfires of Gozan (five high-ranking Zen temples in Kyoto), which color the late-summer sky of Kyoto, originated from his handwriting.
一説には京都の晩夏を彩る五山送り火の大文字焼（如意ヶ岳）の「大」字は、横川の筆跡によるものだという。