People's physical constitutions differed. Some were born deficient, while others possessed powerful bodies from birth.
But there was another kind of person: normally brimming with vitality, with exceptional recovery and stamina, yet unable to live past middle age. They exhausted their lifespan early and died miserably.
Without knowing that Minagawa Uchiha possessed a Sage Body, Might Guy saw someone so young displaying stamina no weaker than that of an ordinary Jonin. Rather than being delighted by his extraordinary talent for Taijutsu, he worried that Minagawa Uchiha suffered from a disease that drained his lifespan.
So, when they passed the training ground again, Might Guy called a halt to their warm-up run!
Seeing that they had not completed their scheduled laps and that Minagawa Uchiha clearly still had energy to spare, Kakashi knew something must have happened. Perhaps something had occurred in the village. Worried, Kakashi immediately stopped training and went to find out.
When Kakashi arrived before the two of them, he saw Might Guy staring gravely at Minagawa Uchiha. It did not look as though something had happened in the village; rather, it looked like Minagawa Uchiha himself had a problem.
Unable to make sense of it, Kakashi did not speculate wildly and directly asked Might Guy:
"What is it, Guy? Is there something wrong with Nanga?"
When Might Guy saw Kakashi arrive, he stopped staring at the bewildered Minagawa Uchiha and turned to the approaching Kakashi.
"Kakashi, does Nanga have some kind of illness? His stamina is highly abnormal. At his age, he can actually keep up with me for so long. I suspect he can only do it at the cost of his lifespan. Come take a look too."
Hearing Might Guy finally explain the reason, Minagawa Uchiha breathed a sigh of relief. The other man's grave