In "Eimeiyawa," the following description is included as what Koan WATANABE talked: 'The handwriting of Gongen-sama (Ieyasu) is as bad as that of persons who had no knowledge of writing.'
ただし、直筆文章とされる書状などを見ると読めないような悪筆ではないため、当時流行の筆捌きでないと言う意味かもしれない。