According to the TV program which showed handwriting analysis of letters written by Tenkai and Mitsuhide, Tenkai was a different person from Mitsuhide, but several similar characters were seen and they were estimated to be close relatives, such as a parent and a child.
テレビ番組で行われた天海と光秀の書状の筆跡鑑定によると、天海と光秀は別人であるが、類似した文字が幾つかあり、2人は親子のような近親者と推定できるという。