The first letter was directed to 'Torei Kinran,' the third letter to 'Shikan Zasu' (the head priest of the Tendai Sect), both of which show that Kukai replied to a letter by Saicho.
1通目の宛名は「東嶺金蘭」、3通目は「止観座主」とあり、ともに空海が最澄の消息に答えた書状であることがわかる。