It is "Iya Yotsugi" that is equivalent to the historical narrative called 'Kagamimono' which concerned the reigns of the both Emperors. (Yotsugi is another name of "Okagami," and "Ima Kagami" also has a different name of "Shoku Yotsugi.")
この両天皇の時代を扱った「鏡物」と言われる歴史物語に該当したのが『弥世継』である（世継とは『大鏡』の異名であり、また『今鏡』も『続世継』という異名を持っている）。