Sarutobi Hiruzen was satisfied.
Ever since he can remember he always struggled, his oldest memories are of his training with his Sensei Tobiramma and sometimes of his father imparting a piece of wisdom to him.
His efforts for improvement were definitely something he doesn't regret, the blood, sweat, and tears he spent on training bore fruit and he became one of the strongest and he prided himself on that.
Sadly no matter how much you train there is an enemy that no one can win against, the most formidable but also the one you can learn the most from, time. Time is implacable, relentless and even the oldest of the beings in this world will fall to its powers.
Sadly Sarutobi Hiruzen is one of such beings, he isn't that energetic young man anymore, and he is reminded of it every morning, his bones are losing their l.u.s.ter and strength, his prior strong muscles are atrophying in a combination of age and inaction, thankfully one of the jobs of an old man like him is helping to guide the new generation.
And what new generation he has in hands, sometimes he even ask himself how come such brilliant people have been born at the same time, he definitely doesn't know-how, he is just happy that they are, he has even chosen his successor.
Training his successor was a fairly easy but time-consuming affair, the boy practically oozes talent and even if he wasn't his first choice, right now he is pretty satisfied with him, after such a long time training him he can definitely say he and the boy did a good job.
So it was with a fairly good mood that he decided to take his daily walk in his village, he would slowly walk on the streets looking at the smiling and happy inhabitants, and sometimes he would stop by a food stand and eat different meals, his favorite one right now is the new Takoyaki stand, the flavor is simply divine, besides the lingering taste combined with his tobacco give him great satisfaction.
So it was a with great surprise when he felt that great shockwave of chakra, in his vast experience with this kind of matters he can safely say that such a huge pulse is an indication of a world-destroying fight, last time he fell something slightly similar he was nothing but a child, but even from far away at the safety of his village, he felt the epic fight of Hashirama vs Madara, even if his memory is getting fuzzy with age, some events are impossible to forget.
For anyone whos was observing the Hokage at that moment they would surely be able to say how much Hiruzen changed in mere seconds, the kind grandfather became the killer he is known for, it started with a slightly change of expression, followed by a sharper posture like a panter close to jumping on its prey jugular, a very good sensor would be able to tell the differences on his chakra that passed from a calm lake to a raging ocean in mere moments, and in the blink of an eye, the Hokage was gone.
In a burst of speed, Sarutobi reached his office, and the moment he entered all the Anbu present know today wasn't going to be an easy day, the Hokage rarely enters his shinobi mode as they called it.
"Anbu, some of you must've felt the chakra shockwave, right now I am going to investigate the source, immediately activate the protocol Kazuki. And I want all troops focused on defense, no question asked"(Hokage).
"Yes Sir"(Anbu).
Suddenly innumerable individuals that priorly were still sprung to life, all the shinobi facilities of the village entered a state of emergence and protocol Kazuki was initiated, the Hokage ditched his robes and entered his personal armory putting on his old armor and getting some supplies.
Not saying even one more world to his Anbus the Hokage now fully equipped burst through the window and went at max speed towards the chakra shockwave.
On the way towards the battle he can even feel the shockwaves becoming stronger and stronger, his mind wandered searching for the infinity of possibilities immediately making plans for the worst-case scenario, sadly life awaits no one so he was quickly able to reach the battle site.