The Kokūzō-Bosatsu Nenju Shidai (canons for the worship of the Bodhisattva Akāśagarbha) owned by the Ishiyama-dera Monastery, Otsu, discovered in 1941 by Messrs. Sakamoto and Takeuchi of the Research Institute of Historical Materials at the Tokyo University, is a horizontal scroll written in China ink on paper, 353.1 cm. in total length and 30.6 cm. in width. The reverse side of this scroll has inscriptions of manuscripts dated the year Kōho 3 (A. D. 966) and several letters including those written in kana (Japanese syllabics cripts). The letters in kana among them are especially notable, for they are as many as thirty years older than what has heretofore been considered to be the oldest kana letter in existence. They are all the more important because they are the first examples of their kind dating from about the time of the death of Ono-no-Tofū, (894-964), the all-famous calligraphist. The first chapter of this essay is the introduction. The second chapter is an outline information of the present state of the scroll, which consists of eighteen fragmentary sheets of paper assembled together. The third chapter gives a survey of the inscriptions found on the reverse side of the paper. The inscriptions can be classified into three groups: two official reports, one by Hōchin and the other by Kintada, both dated March of Kōho 3 (966); four letters, by Fujiwara Kiyomasa, Fujiwara Morouji, Fujiwara Tamemitsu, and an anonymous person, respectively, and four private letters in kana, all without the names of the writers. These writings remain in eighteen separate sheets, which have been assembled into a horizontal scroll. The text of the Nenju Shidai is written on the other side of this scroll. The present author presumes that the text was calligraphed by the priest Kanchū, the head of the Ishiyama-dera Monastery in the fourth generation, who died in the year Teigen 2 (977) at seventy-two. This ascription is only a conjecture at present as we lack enough information about the activity of the priest, but at least it can be safely asserted that the calligraphic style for the text reveals the mode characteristic of the 960's. This means that the inscriptions on the other side of the scroll can not be later than 960's. The fourth and fifth chapters are devoted to the description of those inscriptions, and the sixth chapter discusses their importance in the history of Japanese calligraphy. The inscriptions on the reverse side disclose several different styles ; among the four letters in kana, particularly, we distinctly notice three different styles. It is significant to know that these three calligraphic styles existed concurrently in about the 960's. The letters in kana are especially valuable. The first style reveals the manner of brushwork closely resembling that of the writings attributed to the noted calligraphist, Ki-no Tsurayuki, and it affords us an important source of reference in the study of Tsurayuki's art of the writing brush. The second proves that already in that period there existed the “continuous script,” that is, the manner of writing several syllabic scripts in an unbroken stroke of the brush instead of writing each character separately. This fact necessitates the re-editton of the history of kana calligraphy. The third is that we have found here exemples in which the lines of a letter are even both at the top and the bottom (that is to say, the beginnings and ends of the vertical lines are straight). The oldest letters in kana known heretofore were of later dates, and were all written in “scattered writing.” The last chapter, seventh, lists the names of the calligraphists of those times (10 th Century) mentioned in literary sources. Hitherto the calligraphic art of that period has been explained as represented by the sequence of three masters, from Ono-no-Tōfū through Fujiwara Sari to Fujiwara Kōzei. The discovery of the above-mentioned manuscripts, however, suggests that we have to admit the existence of other contemporary lineages.