Madara has been in a mission for 2 months and it was a dangerous mission. When he returned giving his report to hashirama he looked fine. But by passing days he was getting weaker and weaker. His already pale skin got even paler, he had pain at nights sometimes he was trouble breathing and he couldn't sleep. The dark circles under his eyes were getting darker. And the list goes on. What he didn't know that one of the enemies in the mission putted a strong yet hidden chakra inside his body and that foreign chakra was attacking his system one by one and slowly making damages. Hashirama who could see his best friend getting weaker and sicker by passing time got more and more concerned but whenever he asked Madara what was going on Madara would answer with "I'm fine" or "nothing is wrong". And that made hashirama Even more concerned.