Another year

In this year, after intense training, Ren finally could circulate his chakra slowly. Although his control over chakra is nowhere close to properly use all his power completely. The first technique he learned was none other the signature skill of Naruto, 'Shadow Clone Jutsu'. Although it is a B rank technique, it's potential is almost S ranked if used properly. Just the fact that the user's chakra is evenly divided between themselves and their clones i.e. creating one clone will give it half the user's chakra, creating two clones will give each a third of the user's chakra, and so on, and the clone's experiences and remaining chakra are transferred back to the user; is a great help to Ren. He can divide his huge amount of chakra and slowly practice his chakra control.

After learning the hand signs from Minato, he practiced some time to get familiar with it. This was going to be his first jutsu performed ever, so he was extra careful. The first time he performed the jutsu, he created 200 shadow clones, without breaking a sweat. Checking his amount of chakra with his byakugan (yes he finally started to do something with his byakugan), he was finally relieved. Now he could truly start his journey to the peak.

Ren started the general training methods for improving one's moulding and manipulation of chakra. He began the Leaf Concentration first. This training method is done by placing a leaf over an individual's forehead and having them direct all their chakra onto the leaf, using it as a focal point. His experience with meditation and simultaneously using so many clones, helped him to master it in one day.

Next was Tree Climbing. This training involves focusing a fixed amount of chakra to the bottom of one's feet, and using that to climb a tree without using one's hands. If the stream of chakra is too weak, the user will lose their footing on the tree and fall off. If it is too strong, the user will be pushed away from the tree, causing the tree to break around the point of contact and the user will fall. Ren and his clone army started practicing it in a far away forest from Konoha to maintain his secret. Minato would teleport him their in the morning and fetch him back in the evening. Within 2 days, he mastered it completely.

After gaining experience in the previous 2 methods, Water Surface Walking exercise became somewhat easier. This training method is used to gain better chakra control. To do this, the user has to be emitting a constant stream of chakra from the bottom of the their feet and using the repellent force to walk across the water's surface. This technique is more difficult to master than the Tree Climbing Practice, because the amount of chakra that needs to be emitted changes constantly. But for Ren, the least he fear is running out of chakra. He didn't their, he started practicing running on water, skating on water and continued till he could do all the above without even noticing it or basically even trying. Then he tried to do the same with other body parts that makes contact with the surface of the water. He even mastered climbing atop the water as if he was climbing out of a pool.

All these exercises took altogether 2 months. After this, he could finally use his chakra to learn other jutsus. He didn't try to create more chakra by moulding his spiritual and physical energies. He had inherited a huge amount of chakra, comparable to one tailed beast, from his mother. In 11 years, his chakra amount only increased naturally and when his Rinne Sharingan awakened, his chakra amount increased to another level. Now his chakra level is almost close to nine tails. His Otsutsuki physic, constant physical training and his mother's seal helped him not to explode. Till now he hasn't fully unsealed his chakra. He determined that, it would take another year of hellish training to completely unlock his chakra.

He asked Kushina spar with him to quickly adapt and increase his combat experience. His spar with Kushina couldn't called be a spar, it was a beating. Kushina's improvement in the last year was tremendous. She could now control upto five tails mode. Following his advice, she also tried to merge Kurama's chakra with her body. After one year, she finally showed some results. Her cell vitality increased. Without Kurama's help, she could regenerate small cuts in matter of seconds. She also gained more chakra. She could now definitely be compared with tailed beasts. She gained an additional Yang nature transformation. Though it has not reached a high degree of familiarity, Ren's idea was confirmed. Chakra can change ones physic and carry out some mutation. This must be what happened after Hagoromo shared his chakra with normal humans. His chakra must have transformed their physic and spirit which passed down to future generations. At some point in history someone must have discovered a way to mould spiritual energy and physical energy to create chakra, which led to the start of ninjitsu culture.

That night, he called Minato and Kushina for a discussion.

"Minato, Kushina, what I am going to tell you is going to be extremely important. Don't tell anyone, even your closest relative, about this. The consequences, if leaked, could start another bloody war."

Seeing his serious face, they promised without any hesitation.

"Do you remember, what I told to Kushina before our training? I have finally seen it's result. And it's very good. Minato, Kushina, do you know that I have been thinking of a way to become immortal? Don't take my words lightly. This world has many immortal beings. From what my mother told me, their is a proper way to achieve it. Us Otsutsukis are descendant of one such being. And after our ancestor, many in our clan have tried and succeeded. I want to offer you a chance, will you agree with me to continue in this path?"

Both Minato and Kushina stared at him with mouth wide opened. The temptation of immortality is not a small one. But both of them thought it was somewhat going against law of nature. They would have to throw away something to gain something.

"Ren, does your path consist of harming innocent ones or doing something that would harm them directly or indirectly?" Minato asked him after taking a deep breath.

"You could rest assured that I will do nothing that go against moral nature. You don't know, but I have promised my mother about this. I will never break my promise to her. If I want to, my goal is not so difficult for me. I have already something that will help me. But it is extremely difficult for you. That's why, I am telling you this. You are my closest people after my mother and Aino. I don't want to loose you."

Listening to Ren's word, a smile appeared in Minato's and Kushina's face. After living with him for a year under the same roof, their understanding of Ren has made them to believe him. As for having a longer lifespan, who doesn't want it. If someone can deny it with a strait face, then he is no longer a human, he is a god. In the face of such temptation, everybody will become crazy. If they can achieve it through proper means, then why not.

"Hey Ren, we are with you."

Hearing their words, Ren was very happy. He really wanted them to agree. Now that everything went well, it's time to start his plan.