The strongest fighter across every generation, Naruto’s chakra reserves seem absolutely endless. But why does Naruto have so much chakra?
Naruto has so much chakra because the Nine-Tailed Fox was sealed within him. The Fox Spirit was attacking the Leaf Village, so the Fourth Lord Hokage sealed the demon away within Naruto to protect everyone’s lives.
It takes a long time before Naruto is free to tap into his nine-tailed chakra at will, but he ultimately befriends the beast and is allowed to fully access its strength.
Plot Behind Why Naruto Has So Much Chakra
In chapter #1, Naruto learns the truth behind the mark on his stomach and why the other villagers keep him at a distance. Mizuki, a Chunin and academy instructor, tricked Naruto into stealing a forbidden scroll.
He told Naruto that Iruka would accept him as a ninja if he could learn techniques from the scroll. After a stand off between both adults and Naruto, Iruka explains that the scroll contains a completely forbidden ninja art and Mizuki was using him to acquire the scroll for himself.
Realizing that Naruto was beginning to side with Iruka, Mizuki decided to be cruel and share a secret with him. Twelve years ago, the Nine-Tailed Fox Demon attacked the Leaf Village. The Fourth Lord Hokage trapped and sealed the beast within Naruto to contain it.
Since that incident, the people of our village have been bound by the strictest decree. Part of that decree was that everyone would know about it except you! It was you who murdered Iruka’s family! In other words, you are the nine-tailed fox spirit that destroyed the village! Until, at last, our beloved hero, the Fourth Lord Hokage, trapped and bound you in this form.
Mizuki to Naruto | Chapter #1
While on his first mission, Naruto voluntarily stabbed himself in the hand to help remove poison. Kakashi offers to bandage up Naruto’s wound for him, but quickly notices the cut already repairing itself.
His hand… The wound, it’s almost healed! I should have guessed. It’s the power of the Nine-Tailed Demon Fox.
Kakashi Talking About Naruto
So there’s the answer. Naruto has so much chakra because the Nine-Tailed Demon Fox was sealed within him. Over the series, Naruto is able to tap more and more into the demon’s abilities.