The text of the Ojo uragaki 往生裏書 is owned by the Kanagawa Prefectural Kanazawa-bunko Museum. This is a fragmentary version consisting of 14 sheets and lacking the introductory and final parts. “Ojo uragaki 往生裏書” apparently was a provisional title. The formal title of the work is unknown. However, I compared it with the Ojo yoshu uragaki 往生要集裏書 version in the Shimpuku-temple 真福寺, and my conclusion is that they are almost identical texts and that the original title was “Ojo yoshu uragaki 往生要集裏書”.
The Ojo yoshu uragaki 往生要集裏書 is an an annotation of the Ojo yoshu 往生要集 by Shingen 真源 (1064-1136). The work actually represents an investigation into the textual sources of the Ojo yoshu 往生要集.
I compared the Kanazawa-bunko version of the Ojo yoshu uragaki with the Shimpuku-ji version, and the characteristics of the former became clear: 1) Judging from the number of its Chinese characters, the Kanazawa-bunko version represents a third of the Shimpuku-ji text. 2) The sheets in the Kanazawa-bunko version are not arranged in the correct order. 3) The missing introductory part amounts to about 3 sheets.
The Ojo yoshu uragaki 往生要集裏書 has been so far known only in its Shimpuku-ji version. The discovery of the Kanazawa-bunko version makes it possible to collate the two texts and opens the way for a critical edition. I hope that my diplomatic edition and study will contribute to this.