Hiruzen had carried the responsibilities of the Hokage position right from the end of the First Great Ninja War to the end of the Third Great Ninja War. The era during which he led the village was far more turbulent as compared to the relatively peaceful time Konoha currently enjoyed.
Unlike today, when Suna was weak, Kiri was embroiled in a civil war and Onoki had grown old and wary, Hiruzen had to deal with the neverending schemes of the powerful Third Raikage, a young and more active Onoki, the cunning Third Mizukage and a Sunagakure that was much stronger with several rank S ninjas and promising youngsters among their ranks, all of whom eyed the Land of Fire like hungry wolves. In addition, he also had to watch out for the powerful Hanzo who led the Land of Rain.
Though he hadn't been perfect, he had led the village admirably and had ensured that Konoha stayed strong throughout despite being surrounded by enemies on all sides. He had done his duty of passing the Will of Fire to the next generation by passing the hat to Minato. When he had retired, Konoha had 7 rank S ninjas in Hiruzen, Danzo, Minato, the three Sannins and Uchiha Fugaku along with a matured Jinchuriki and a powerful group of veteran Jounins who had survived through two Great Ninja Wars.
Unfortunately, the Nine Tails' assault caused the death of Minato and Kushina and eliminated the majority of the veteran Jounins in Konoha, directly pushing Konoha from being the strongest village to a vulnerable one. Hiruzen didn't want to let the two people who competed with Minato for the Fourth Hokage's seat become the Hokage as Orochimaru grew increasingly dark while Fugaku was suspected to be behind the Nine Tails attack.
As a result, Hiruzen had to take the Hokage seat once again. Unfortunately for him, the conditions were far worse than merely the village being vulnerable due to the losses. The powerful Uchiha clan had to be treated with suspicion due to the Nine Tails Assault. Danzo's dreams of becoming the Hokage reignited with Minato out of the way and Jiraiya and Tsunade showing no interest in the position. He created more and more problems for Hiruzen which he failed to curb in time. And, Orochimaru became increasingly dark to a point where he was considered beyond saving and Hiruzen had to exile him.
Hiruzen's second stint as the Hokage was a mere shadow of what he had achieved during his initial reign. Being as smart and experienced as he was, he could see it clearly. Unfortunately, he hadn't been able to handle the matters as efficiently as he could when he was younger. In his old age, he had been reluctant to be as decisive as he once was.
Even after Minato's death, Hiruzen had done well in keeping Konoha's enemies at bay. Apart from the Hizashi incident, Konoha didn't suffer any significant loss at the hands of enemy villages. Of course, the weak situations of the other villages were a big help. However, when it came to internal politics, Hiruzen had performed miserably during this time.
Every time it felt like the village would stabilize after a lot of effort, the village would be hit by something that would set it back several years. And that 'something' would always be an internal issue in Konoha which he should have handled long before it reached such a level.
It was what exhausted Hiruzen to the point that he became tired of the job. And yet, he had no choice but to continue sitting on the post as no one who was qualified was willing to accept the responsibilities of the Hokage seat.
Hiruzen couldn't continue sitting in his office for a long time. After feeling pity for himself for some time, he got up and began dispatching the Anbu ninjas to cooperate with what Shikaku and the other clan leaders were doing. In addition, he left to see Torune and the other four Root ninjas who were with his Anbu Guards.
The Anbu Guards had woken the five of them up. Fujin's clones had only knocked them unconscious while placing seals on them. It wasn't difficult to heal and wake them up. On seeing Hiruzen, they all became serious. Hiruzen asked some questions which they answered truthfully.
On hearing them, a peculiar expression appeared on Hiruzen's face. He thought, 'That's it? Are they hiding something or is this all that happened?'
Hiruzen thought for a bit and concluded, 'I doubt they will lie to me. Besides, they were indeed spying on Fujin. Considering Fujin's nature, things might have developed in this manner. Regardless, I should call him tomorrow as well in case there are some differences. Hmm, leave it, he and Danzo might break into a fight. I'll just confirm during the council meeting. Still'
As Hiruzen heard what actually happened, he couldn't help but think how small the incident was. It was merely spying along with a small clash with no casualties and yet the incident had blown up spectacularly in Danzo's face. Hiruzen couldn't help but think, 'No wonder Danzo's expression showed that he was facing injustice. He has pulled stunts a hundred times worse than this on a regular basis for decades and didn't even face so much as a complaint, but this minor incident nearly cost him everything!'
Hiruzen couldn't help but find the situation funny. It was as if a serial killer who had killed his victims for decades and managed to stay safe from police had suddenly been apprehended because of an insignificant petty crime he committed!
Hiruzen left the Root ninjas with his Guards and began monitoring the efforts to look into the incident and investigate the village. Unfortunately, it became clear very soon that it would be another fruitless search. Hiruzen gave up on it once the Sun rose and called Danzo to meet the Root ninjas.
After learning what had actually happened, Danzo exploded in rage once again. He looked at Hiruzen and shouted, "If he hadn't insisted on stopping them, Torune wouldn't even have attacked him. Are you going to punish me because Fujin acted so willfully even when such a big attack had happened in the village?"
Danzo truly was infuriated. He had thought about what happened in Hiruzen's office all the time and kept feeling as if a grave injustice had happened against him. On learning what truly happened between the Root ninjas and Fujin, he couldn't keep his calm anymore.
The only reason why Torune and others were discovered was because Root was attacked! Similarly, the only reason they attacked was because Fujin was too stubborn to let them go. Considering that the Root headquarters was blown up, Danzo couldn't even fault them for wanting to return immediately. Yet, Fujin used this incident to make the situation miserable for him by giving everyone one-sided information. In fact, Torune didn't even intend to kill Fujin and would have neutralized the poison, but Fujin presented the matter as if Torune wanted to assassinate him!
Hiruzen had expected Danzo to explode in this manner. It was why he hadn't called Fujin. Besides, having known Fujin for so long, Hiruzen knew exactly what he would have said. After thinking for a bit, he decided to speak in the same tone.
Hiruzen said, "Well, it is a fact that you sent them to spy on Fujin, a Council Member. Just that alone makes your punishment justified, something that the clan leaders will press on. Even though Fujin ignored the situation, he wasn't wrong in asking them to come with him. He didn't attack first either. Attacking a Council member under these circumstances is nothing short of treason.
Besides, the attack took place inside of Konoha. I and several hundred ninjas were heading towards the Root within seconds. In such a situation, cooperating with Fujin should have been your only thought."
Hiruzen's words were a huge blow to Danzo, who became lost for words. He understood that Hiruzen wouldn't be budging no matter how well he argued. At the same time, he also understood that the clan leaders too wouldn't relent even if the matter was so small. He could do nothing but curse Fujin who blew up such an insignificant matter.
Danzo removed the seals on the bodies of Root ninjas and began walking out. The Root ninjas followed him in confusion as they wondered what Danzo meant by being punished.
As they left, Hiruzen said, "Danzo, you have till noon to inform me which ninjas you will be keeping. The rest need to visit me in my office."
Danzo looked at Hiruzen once but left without saying a word. Torune and the rest were confused. After they left the room, Torune asked, "Lord Danzo, what happened in the headquarters last night? Also, what did you mean by getting punished?"
Danzo didn't say anything until they reached the labs under Root. He informed the 5 of them what had happened. Torune and the other 4 were immediately shocked. One of them complained, "That's so unreasonable! We only attacked because he had surrounded us and drawn his swords. Why are you getting punished for it?"
Another one added, "Though this is injustice, we can take the blame and say that we did it independently and without your orders. That way, even though we will have to sacrifice ourselves, the Root will prosper."
Danzo replied, "It's useless. Hiruzen and the others won't relent even if you do something like that. They are only using this opportunity to take the Root out."
Danzo looked at his subordinates and said, "Even if I have to let some of you go, don't forget that you are a part of Root. Konoha will always need us to ensure that the village stays peaceful. In the future, the village will need us once again. At that time, I'll call you all back and we will reform Root once again!"
Danzo's image, which was already heavenly in their hearts, improved even further. Despite facing such injustice, he still wanted to serve the village. Since he only had a few hours, Danzo spent them increasing his influence on his subordinates further. He didn't want to let Hiruzen brainwash them like he did with his previous subordinates. Danzo had little to no chance of recruiting them once again.
Unfortunately, the kids kidnapped from the Land of Water were too far away. As such, Danzo didn't get an opportunity to brainwash them as well.
Sitting in his office, Hiruzen wondered, 'What should I do with those Kiri kids? They could have stayed hidden in the Root and wouldn't have raised any questions. But if I bring them in the open, there is a chance that their identity will be leaked. If that happens, Konoha's reputation will plummet hard.'
He thought for a while when he suddenly had an idea. He thought, 'Yeah, this might be the best way to deal with them.'
A mischievous smile appeared on Hiruzen's face. He looked at his guards and said, "Invite the Council Members for a meeting. Don't invite the civilian members."