As Uchiha Tajima had said, to attain the greater power of these eyes, one was bound to lose something.
Although Tajima and Uchiha Long had previously planned to use an outsider like Nariya Ueshima to awaken Madara's Mangekyou Sharingan partly to spare the Uchiha clan from casualties...
Now that it was Izuna's turn to awaken his eyes, reality forced him to go against that very intention.
Chapter 137