Old men die, because it was all they had left to do. Old women die, because they had nothing left either. They died one by one, and everyone else had to watch. Watch and cry, and grieve, and joke about it later, and ask unanswerable questions. Because they must mourn everyone-no matter how little good it does anyway.
And the young live. The young live because of everything they have left to do, and live for, and live with. Whether they live happily or not, is a different equation. But they will live until they too are old, die because that is what they must do. They are the ones left to mourn the old who have died, and the ninja who are left and still dying.
Ninja die. There is no young or old for ninja, because there is no way to measure the time they spend as ninja. A lifetime experienced in weeks, days, minutes. Traitors made in seconds, a hero in another. Deadly in one moment, and then pitifully weakened in another. Those are the lifetimes ninja live in the crucial moments they try to survive.
This world leads to cold lives, and warm memories, revenge, hatred, love and remembrance. It leads to the young having to cry over the old-and the ninja. It leaves the old regretting and wondering and wishing. And it leaves the ninja, sitting like faded pictures to cry over, leaving them to take too many missions and get themselves killed because they use too much chakra, or there's too much blood, or too many enemies, and just not enough strength and willpower left.
Because old men die, and old women die. And the young are meant to live-even if some of them live in misery, and even when some die too young. And ninja just die, because they cannot really control it, because they live to defend their village and their homes and their loved ones, when it all comes down to one moment.