In Naruto, many villains gave the Konoha shinobi and the free ninja world a run for their money. The Uchihas, such as Itachi, Obito and Madara, are prime examples, as are the Akatsuki and Kaguya. However, the would-be Hokage was always on hand to save the day, working with the likes of Sasuke, Sakura and Kakashi to ensure the world wouldn't be destroyed. But, in the Boruto anime, Naruto admitted his dirtiest secret when it came to these endeavors -- and it's all due to Kurama's death.
Source：https://www.cbr.com/boruto-episode-219-kurama-death-naruto-secret/
