In Kazunaga SUGAWARA's diary, "Higashiboujou Kazunaga Kyouki", he wrote on August 1st of 1494 that "it is said in secret that the monk IKKYUU is a prince, the illegitimate child of Gokomatsu.
菅原和長の日記『東坊城和長卿記』明応3年（1494年）八月一日の条に、「秘伝に云う、一休和尚は後小松院の落胤の皇子なり。