Naruto is an influential anime that features many charismatic characters known for their incredible skills and endurance. Among them are a few ninjas who are incredibly ruthless towards themselves. Deidara, known for his explosive art, modified his body to incorporate mouths that could make detonating clay. But his ultimate technique, C0, involved eating explosive clay with his chest mouth, leading to a massive self-destructive explosion. Hidan, a follower of the Jashin religion, enjoys killing his opponents while using a curse that causes him to share their pain and eventually die himself. Then there's Kakuzu, who uses his own body as a puppet to achieve immortality but can be killed by targeting his heart. Lastly, the Eight Gates technique used by Might Guy, Might Guy, and Rock Lee inflicts extreme pain on the user, but they embrace it and find joy in surpassing their limits. These ninjas' cruelty towards themselves is truly remarkable.
