Hiruzen smiled bitterly, 'He really does make the most of every opportunity!'
He said, "Unfortunately, you can't learn that right now."
Fujin showed a thoughtful face and asked, "Why not?"
Hiruzen answered, "To learn Flying Thunder God jutsu, you need 2 things. You need to be a Fuinjutsu master. For that, you need to learn every Fuinjutsu seal from our Library and be able to make them with ease. In our village, there are less than 10 Fuinjutsu masters.
Secondly, you need to have a talent for Space-time ninjutsu. And that talent is very rare. I am only aware of 5 ninjas from Konoha who had talent in it."
Fujin thought for a second and asked, "If I become a Fuinjutsu master, can I be allowed to learn it then?"
Hiruzen chuckled and said, "Sure. But learning Fuinjutsu is difficult. I would suggest you not waste time on it right now."
Hiruzen asked, "Do you have anything else you want to learn?"
Fujin nodded once again. Hiruzen was surprised, 'He even thought of something else to ask if his request was denied?'
Fujin said, "I heard that one of your students, the Toad Sage Jiraiya of the Sannins, can use Senjutsu. Can you teach me Senjutsu?"
Hiruzen was shocked once again! He wondered, 'Am I getting too old to teach the new generation? Where did he even learn about Senjutsu?'
Mieko and Hoka looked at Fujin with confused faces, 'What is Senjutsu?'
Hiruzen asked, "Where did you learn about Senjutsu?"
Fujin replied, "I read it on a scroll in the library."
Hiruzen wondered, 'Did he read every scroll and book there?'
Hiruzen said, "Unfortunately, I can't teach it to you as I don't know it."
Fujin acted surprised and exclaimed, "Even you don't know it? Then could you arr…"
Hiruzen cut Fujin off and said, "Just like the Flying Thunder God, you won't be able to learn Senjutsu either. The basic requirement to learn Senjutsu is having a lot of chakra."
He then began exerting his chakra, showing it to Fujin. He said, "You will need more chakra than me to be able to learn Senjutsu."
Fujin, Mieko, and Hoka were surprised at how much chakra Hiruzen had! It was around 150% higher than Renjiro's! Fujin wondered, 'Even at such an old age he has this much chakra? It is almost 18 times larger than my chakra!'
Fujin sighed thinking, 'How long will it take me to reach that level?' He said, "Alright Lord Hokage."
Hiruzen had enough of asking Fujin what he wanted to learn. He was afraid of what Fujin might ask next. However, before he spoke, Fujin asked, "Lord Hokage, can you teach me Wind Vacuum jutsus then?"
Hiruzen's eyebrows twitched. He wondered, 'Did he find out about them in the library as well?'
Fujin looked at Hiruzen thinking, 'I knew that I couldn't learn Flying Thunder God and Sage mode. Even if I could, I doubt he would just give me the scrolls or the guidance needed to learn them. Minato probably only got them as he was Jiraiya's student.
But if I didn't mention those two and directly mentioned Wind Vacuum jutsus, it's likely that he would have rejected me due to how dangerous they are. But now that he has already rejected me twice, it's unlikely that he would reject me once more.
The only concern left is whether he'd ask Danzo to teach me. But seeing his Air Palm jutsu, I'm betting that he knows Wind Vacuum jutsus as well. Even if he asks Danzo, as long as Danzo doesn't make me join the Root, I don't care much about him. After all, he doesn't have Shisui's eye yet. And by the time he gets it, the Root will be dissolved. Well, at least officially that is.'
Hiruzen thought around the same lines as Fujin analyzed, 'Wind Vacuum jutsu… It is very lethal. Not something I want to teach to little kids. But I have already rejected him twice. Saying no once again won't look good. Not to mention, it is much safer than Senjutsu and Flying Thunder God.'
He decided to teach him. Hiruzen nodded, "Alright. I'll teach you Wind Vacuum jutsus…" He realized what he said!
Fujin immediately smiled and bowed down, "Thank You, Lord Hokage!"
Hiruzen looked at the 11 year old kid with disbelief, 'I promised to teach them one jutsu! He made me promise to teach him all the Wind Vacuum jutsus. And he even thanked me so quickly…'
Hiruzen sighed internally and decided, 'Leave it. I'll teach him and get him off my back for now. Though in the future, I need to ensure that I don't promise him any rewards.'
Unfortunately for Hiruzen, he had already promised Fujin something for the future. While he didn't think that future would ever arrive, Fujin had already sealed those words in his memory!
While Fujin didn't have enough chakra to use Shadow clones for training ninjutsu, especially when he was mastering rank B jutsus or supercharging jutsus, he had plenty to abuse while learning Fuinjutsu!
As soon as he mastered all fuinjutsu available, he would ask Hiruzen to aid him in learning Flying Thunder God. By then, he would even have built a good reputation in Konoha, so Hiruzen would be more likely to agree.
Hiruzen made a couple of shadow clones. Hoka and Mieko went with one each while his main body stayed behind with Fujin.
Hiruzen looked at Fujin and said, "Fujin, before I teach you, I need you to promise me something."
Fujin asked, "What Lord Hokage?"
Hiruzen replied, "The Wind Vacuum style is very dangerous. Never use these jutsus on a colleague or an ally. In the future, you would likely spar a lot with other ninjas from Konoha. Under no circumstances are you allowed to use Wind Vacuum style against them."
Fujin nodded and answered without hesitation, "I agree, Lord Hokage. I don't even use my sword while sparring."
Hiruzen nodded. It was the main reason why he agreed. He said, "Excellent. I will now first explain the theory of the Wind Vacuum style. Once you understand, we will begin learning it."
Fujin nodded and paid attention. Hiruzen's clones also began teaching Mieko and Hoka.
Mieko had the Sharingan, so she very quickly got the basics of the jutsu. But actually performing it was much tougher as it was an A rank jutsu! She couldn't form the ring of fire around her.
Hoka too got stuck in creating a Vacuum shell. Both would need some time to overcome those obstacles. However, once they did, they would advance rapidly.
Fujin too had a tough challenge to overcome!