He also argues 'that the theory which states that Shotoku Taishi was created in the Nihonshoki is doubtful because the letters 'Shotoku no Sumera' appear on 'To Robanmei' of Hoki-ji Temple, which was made 14 years before the completion of the Nihonshoki and that Oyama's theory is largely based on supposition and lacks sufficient evidence in insisting that the Robanmei is a forgery.'
また「日本書紀が成立する14年前に作られた法起寺の塔露盤銘には聖徳皇という言葉があり、書紀で聖徳太子を創作したとする点は疑問。露銘板を偽作とする大山氏の説は推測に頼る所が多く、論証不十分。」とする。