Death and tragedy are common in the world of Naruto. The ninja lifestyle is brutal as anyone could be cut down at any moment. Despite all of the uncertainty and cruelty that exists, the heroes of the series constantly die smiling. When each character meets their end, they are not overwhelmed with fear, anger or regret. They die without complaint and with contentment. This contrasts greatly with the death scenes of many villains like Orochimaru, Sasori and Hidan, who greet their demise with resentment and terror. So, why do the heroes die with a smile and the villains don't?
The Will of Fire
The philosophy of the Will of Fire is mentioned often throughout the series by characters such as Hashirama Senju and Hiruzen Sarutobi. The ideal of the Will of Fire is that everyone living in the Hidden Leaf village are a family, dedicated to protecting and loving one another. The villagers gain strength and willpower from this ideal during times of crisis. Another aspect of the Will of Fire is that the dreams and goals of the previous generation can be passed down and fulfilled by the next generation. Due to this, ambitions never die, even if the original owner of those dreams do. At the end of the Fourth Shinobi War, Hashirama explains this concept to Madara before they both return to the afterlife:
"Our job is to do all that we can while we're alive. And then bequeath the rest for future generations to accomplish."
Hiruzen Sarutobi
During the final part of the Chūnin Exams, the Hidden Leaf village was attacked by ninja from the Sound and Sand. While the assault was taking place, Hiruzen was forced to fight his former student, Orochimaru. Although Hiruzen attempted to kill Orochimaru, he ultimately failed. Orochimaru promised to destroy the Leaf with his forces as Hiruzen collapsed. Despite these threats, Hiruzen still smiled contently as he passed away. He smiled because he believed in the Will of Fire and had faith in the Leaf ninjas he had raised and trained. Even though he'd failed, Hiruzen was sure that the next generation would continue his dream of protecting the Leaf Village. His last words confirm this:
"When the tree leaves dance, one shall find flames. The fire's shadow will illuminate the village, and once again, tree leaves shall bud anew."
Chiyo
A character doesn't have to hail from the Hidden Leaf Village to believe in some form of the Will of Fire. Chiyo was an advisor to the Hidden Sand Village and was the one to seal the Shukaku inside of Gaara. She had little faith in the next generation of her village and was very suspicious of the alliance with the Leaf. After seeing Naruto and Sakura's dedication to Gaara and other Sand ninjas, Chiyo's perspective changed. She decided to put her faith in the next generation and allow them to correct the mistakes of the past. Chiyo willing sacrificed her life so that Gaara could be revived and lead the village into the future. She explains her new outlook to Naruto while bringing Gaara back:
"I'm happy that someone like you has appeared in the world of shinobi that we foolish old people created. Everything I've ever done was a mistake. But now, at the end, it looks like I'll finally be able to do the right thing. The Sand Village and Konoha. Their future will be much different than the way things were back in my day."
Jiraiya
Despite being a world-renowned ninja and a member of the Sannin, Jiraiya personally viewed most of his life as a long list of failures. He was unable to win Tsunade's heart, stop Orochimaru, save his master Hiruzen or protect Nagato, Konan and Yahiko. Even during his last fight, he was unable to defeat Pain. Regardless of all of these shortcomings, Jiraiya died with a wide smile as he sank to the bottom of the ocean. Hiruzen passed down the Will of Fire to Jiraiya, who in turn passed it down to Naruto. Jiraiya felt certain Naruto would accomplish all of the things he never could. His dream of peace lived on through Naruto. With his final words, Jiraiya trusted Naruto to finish his story:
"There, that ending…was a little better. The frog at the bottom of the well drifts off into the great ocean. Heh heh…yep…pretty damn honorable…pretty damn honorable…I guess it's time to put down my pen. Right…I need a title for the next book…let's see…ah, got it…The Tale of Naruto Uzumaki…perfect."
Neji Hyuga
Early in the series, Neji believed that a person's station in life could never be changed. He accepted that his fate was set in stone too. After his fight with Naruto, he realized that people could choose what kind of person they could be. Neji chose to become strong enough to protect the people he cared about. This eventually led to him giving up his life for Hinata, embracing the Will of Fire. No one forced him to sacrifice himself, it was a choice made of his own free will. In the end Neji passed on without regrets because he died saving his family. He believed Naruto would continue carrying his dream of protecting the people he cared for. In his words:
"Father, I finally understand your feelings…The freedom you felt when you chose to die to protect your friends…"