"Listen carefully, what we tailed beast know from father about Princess Kaguya. She is actually the mother of both twins Hagoromo and Hamura Otsutsuki. As they inherited her chakra, they both can use chakra from birth. About Kaguya's past, father didn't tell us much. We only know that she once cast a spell, which made all humans bound to a tree known as God Tree. The tree absorbed their energy and energy between heaven and earth. Earth was slowly dying. Only for handful of people and beast, everyone were enslaved. The two brothers after knowing the truth, fought against her. Father had awakened Rinnegan and his brother also awakened a power equal to Rinnegan. Kaguya transformed the God Tree into Ten Tails and controlled it to collect the chakra passed from her to her two sons. With the help from Mount Myoboku's toad Gamamaru, they fought for days. At that time destruction spread everywhere. Seas dried up and mountains were flattened. After days of fighting, they discoverd that they cannot kill their mother. She was too powerful and she was immortal. Like us tailed beast can't be killed, she was like a human shaped tailed beast. They decided to seal her using a powerful seal. They had a feeling that their mother never used her full power against them. They don't know, if it was her kindness or greed to capture them and take their chakra. So, taking advantage of her carelessness, they sealed her creating a artificial landmass which is we know as the moon."
When Minato and Kushina know that moon was created by the two brothers, they were shell shocked. From this could estimate how powerful they were.
"After sealing her, father sealed the ten tails inside him and became the first jinchuriki of ten tails. As it's conscious was that of a greedy child, he could suppress it and use its chakra to gain more power for which he known as the Sage of Six Paths. His power was so grate that even 10 Hashirama and 10 Madara fight against him, he could beat them effortlessly. He had mastery over Yin-Yang release, which is one of the most powerful chakra nature release. Hamura went to moon to keep company of his mother. Father journeyed everywhere to help people. After some time he returned to his homeland and started preaching Ninshu. He shared his chakra with others in hope to reform the destruction caused by their battle. He had two sons Indra Otsutsuki, who inherited his spiritual power and Ashura Otsutsuki, who inherited his Sage Body. Indra was a genius. He developed hand signs to allow people to mold chakra easily. Father selected Ashura as his successor as he was hard working and peace loving. Indra got jealous and left. Father started to get weak as his power was distributed. Becoming Ten tails jinchuriki took a toll on him. So he extracted all its chakra and use a technique called 'Creation of all Things' to separate the chakra into nine tailed beasts and gave them consciousness. That's how we tailed beast come to existence. Father gave us a mission to protect and guide humanity. Indra came back for revenge against his brother Ashura. Ashura won as he inherited father's chakra after he became his successor. Indra vowed to destroy Ashura and his descendant by reincarnating again and again. Ashura also vowed to protect them whenever Indra reincarnated. The last of their reincarnation were Hashirama as Ashura's reincarnation and Madara as Indra's reincarnation. That's why they were a league of their own. Hamura's descendant live in moon. Some time in the history some of them returned and lived here. They are the Hyuga clan. I don't know about people living on moon. I never went there."
"Before father died, he told me a prophecy from toad sage Gamamaru that I will come across an individual named Ren Otsutsuki. Their elder brother whom both of them had not seen, only listened to their mother talking about him in great sadness. I think Ren is their brother, the best prove is his third eye known as Rinne Sharingan same as of Princess Kaguya."
Three pairs of eyes fell on Ren. He was somewhat agitated. They all were expeting some answers from me. Ren sighed and told them the truth.
"Yes I am the elder brother of Hagoromo and Hamura. From my time they were not born yet."
Minato asked "Your time? What do you mean by this?"
"Well I am from a time before all this happened. We met an enemy and due to my condition, mother send me into the future to protect me and allow me to grow properly without hiding and running."
This time all three were shocked. If something even Kaguya can't solve, how powerful the enemy would be. Just the thought cause them to dread. Cold sweat started flowing from their back.
Kurama instantly asked "Who is the enemy? Is he coming for you? Where did he come from? How much time do we have?"
He knows the power of Sage of Six Paths. If his mother is more powerful than him and she had to flee from her enemy, you can guess why he is so agitated. Minato and Kushina also have the same thought. Though they can't guess properly, but from Kurama's words, they realized how dangerous the situation is.
"Relax! Mother injured him pretty badly. Even if thousand years have passed, he may not have recovered properly. If worst come to worst, I will unseal mother. Also he doesn't know that I am alive. If we work together, we can defend ourselves. If I am given time, I can reach mother's level and we can fight back. I will also help you in boosting your powers. Moreover, while crossing time-space. I caught glimpses of possible future events. We can use them as reference to prepare ourselves. Though it may cause some changes, but with all of us working together, we can overcome it."
Yes, why should they get scared of an invisible enemy. With Ren's IQ and knowledge, if they use it properly and work hard, they can absolutely do become more powerful and protect everyone.