Battles are a common challenge faced by Shinobi. Therefore, a Shinobi must constantly train their combat skills to become stronger than any potential enemy they may encounter in the future and to prevent the dangers that could arise from being defeated by a more powerful opponent.

In addition to combat skills, maintaining a prime physical condition is also crucial for a Shinobi before facing enemies in battle. Throughout the Naruto Shippuden anime series, there are several characters who were forced to accept defeat because they were suffering from illness, giving their opponents a significant advantage. This unfortunate condition led these ill characters to experience defeat in their battles.

Here are six Naruto characters who lost battles due to illness.

1. Sai vs Shin

As children who lost their parents to war, Shin and Sai chose to join the Anbu Root organization led by Danzo. Danzo trained both Shin and Sai to become Shinobi, assigning them to always be together and live under the same roof. As a result, they developed a bond like that of siblings. Even though they weren’t related by blood, Sai saw Shin as an older brother, and Shin considered Sai as his younger brother.

However, after they grew up, Danzo ordered Sai and Shin to fight to the death, with the survivor being selected as an official member of Anbu Root. This was a difficult task for both Sai and Shin, who had come to see each other as family. To ensure they didn’t disobey, Danzo warned them that if, after three days, they were found alive or had attempted to flee, he would eliminate them both.

The Anbu Root organization was deliberately designed to raise children in pairs so they would develop close friendships and a sense of brotherhood. However, upon reaching adulthood, they would be given the mission to kill their closest friend. As the leader of Anbu Root, Danzo required his subordinates to eliminate their emotions and become merciless. This method was intended to create true and powerful Shinobi.

Sai found it impossible to fight Shin. However, Shin attacked him seriously, slashing his sword toward Sai. Sai was shocked by Shin’s intent to kill him but refused to fight back and continued to dodge Shin’s attacks.

Sai ran and leaped through the trees to avoid Shin, who was chasing him. But suddenly, Shin’s illness relapsed, causing him to fall from the trees. Sai, worried, approached Shin, who was lying on the ground in pain. However, Shin unexpectedly held a kunai to Sai’s throat.

Shin believed that Sai was too kind-hearted to be an Anbu Root member. However, because Shin had already accepted his fate due to his illness, he believed Sai deserved to live. Shin’s condition worsened as he coughed up blood repeatedly. Sai tried to convince Shin to seek treatment, but Shin refused, knowing his illness was incurable.

Since Danzo was unaware of Shin’s serious condition, Shin instructed Sai to report that he had killed Shin. He also advised Sai to erase his emotions so he could carry out future missions as an Anbu Root member without putting himself in danger.

# Reason Sai Defeated Shin

Although Sai emerged victorious over Shin, Shin had actually been suffering from a chronic illness that caused him to cough up blood since childhood. However, he kept this secret from both Sai and Danzo. Unlike Sai, who was unaware that the final Anbu Root test was to kill his comrade, Shin had long known about this brutal test.

The reason Shin hid his illness was so he could intentionally lose to Sai during the final sword-fighting test. However, Shin’s body had become too weak to wield his sword, and Sai had no intention of fighting him. As a result, Shin’s plan to lose deliberately was never realized, and he eventually succumbed to the illness that had plagued him for so long.