The Naikaku-kansei stipulated that "as the head among the ministers, the Prime Minister shall report affairs of state to the Emperor, receive the Emperor's instructions, and maintain unity among the different branches of the administration" (Article no. 2), but the abovementioned "head" meant simply "prima inter pares" (first among equals).
「内閣総理大臣ハ各大臣ノ首班トシテ機務ヲ奏宣シ旨ヲ承ケテ行政各部ノ統一ヲ保持ス」(2条)と定めていたが、この「首班」とは「同輩中の首席」を意味すると解された。 - Wikipedia日英京都関連文書対訳コーパス