Asura and Indra's fated entanglement across lifetimes could be called the hidden main storyline of Naruto.
It elevated the tale of a hot-blooded youth striving all the way to defeat the great demon king and save the world into the story of two brothers fighting endlessly across three lives and three worlds, together exploring war and peace.
In the end, it revealed that peace brought by violence could not last. Only by using love to move people's hearts could true peace be achieved.
Mm...
So, everyone understood why they all seemed so weak in Boruto more than a decade later, right?
As the saying went, skip training for one day and your hands stiffened and feet slowed; skip two days and your skills were halved; skip three days and you became an amateur.
After more than a decade of peace, technology in the Shinobi World had advanced by leaps and bounds, but people...
Ahem...
Though a nation be great, forgetting war invited danger!
Just look at what happened to Aunt Anko! (My heart hurts! Give me back little Anko in her fishnet outfit!)
Another decade or two, and wouldn't she become the Shinobi World's Big Mom?
Ahem, back to the point.
Asura and Indra were the sons of the currently acknowledged supreme god of the Shinobi World—the Sage of Six Paths. They respectively inherited the Sage of Six Paths' Sage Body and Sage Eyes, and were the ancestors of the Senju Clan and the Uchiha Clan.
Because they had different understandings of peace, they began to fight.
In their first life, Indra lost, because the Sage of Six Paths, acting as the judge, admired Asura's idea of moving people with love more.
In their second life, they reincarnated into some unknown generation of their own descendants, becoming Senju Hashirama and