These are my personal reasonings for the list below. Some could’ve had it worse than others but it’s all subjective and views could be different
#1 Gaara
he was ostracized like Naruto and hated and feared because he was a jinchuriki. This left him with great pain in his heart, his own father tried to kill him multiple times, and his uncle betrayed him and blamed him for his sisters death and also tried to assassinate him. His mother the only person that truly loved him died the day he was born. This left gaara going berserk and becoming evil until he was changed by Naruto and was saved from the darkness. Naruto admitted Gaara’s life was more sad than his because he was in the darkness longer. Gaara’s father apologized to him for treating him so poorly and told him mother actually loved him this whole time and the sand protecting him is actually her spirit and that just makes his story all more sad. After reevaluating the story I put him as #1
#2 Nagato
As a child he watched as Leaf Ninja killed his parents. Making him a war orphan, watching as his village was being destroyed by other nations at conflict, he wandered around looking for food and shelter. Eventually almost starving to death and with no one to help him. He eventually met Konan and Yahiko, and they became close friends. They met Jiraiya during the war, who trained them to use ninjutsu jiraiya eventually left them leaving the trio very sad. They created the akatsuki and was betrayed by hanzo, konan got captured and Yahiko died. This was the moment when Nagato became Pain. His pain was so deep he even left Naruto the main character speechless and had no answers for nagato.
#3 Naruto
Naruto’s parents both died the day he was born leaving him an orphan at birth. He had absolutely no one there for him. And spent most of his childhood in isolation. Danzo revealed he was the 9 tails jinchuriki to the village because he wanted to “direct the villagers hatred towards something” after The Nine Tails Attack, because of this Naruto was forbidden from visiting shops in the village, the shop keepers wanted nothing to do with Naruto. He was feared and hated and was treated poorly by the villagers. In the Itachi novels, itachi stated no one in the village suffered more than Naruto. The other kids also didn’t want to play with naruto. He lived by himself with no parents or parental figures. The ramen guy was the only one to feed Naruto after he seen Naruto out in the cold and rain hungry. Naruto’s sensei mizuki that he highly trusted, tricked him and framed him for stealing the scroll and attempted to assassinate him the very first episode! Naruto was an underdog that had to earn his way to the top, he was not respected until he saved the village multiple times and then the world. Sasuke also stated in the shinden novels that he thought about it over again and that looking back Naruto had a much more painful childhood and it’s actually a lot worst to grow up with no one and to never experience love. Naruto having a positive outlook on life made it appear as though it wasn’t as bad but the pain was always there. Kurama came out of Naruto’s body just to tell Kawaki that his life was not sweet. And when Naruto tells his past to his enemies they usually fold and turn to the good side
#4 Sasuke
As a child, he came home and seen his entire clan get massacred and his big brother Itachi standing over their parent’s bodies. His own brother that he always looked up to and wanted attention from. He was beaten up by his brother and had to watch his parents die on repeat for 24 hours which was hundreds of thousands of times over. Unlike Naruto, Sasuke knew what it was like to have a caring family and he lost everything. He was too young and didn’t know about his clans coup. Sasuke experienced shock, grief, anger and ptsd. After the events of his clan he made it his mission to avenge his family and kill Itachi. When he learned the truth he awakened the mangekyo sharingan and grieved Itachi. he had animosity for what the leaf did to his brother and wanted to find answers or destroy the village
#5 Kakashi
his dad committed suicide when he was young leaving him an orphan, and he never really had a mother, she also died when he was young. He lived alone growing up and took care of himself. His teammate obito made him realize his dad’s ideology was correct and to never leave a comrade behind. Obito died getting crushed by a rock leaving kakashi very depressed, he made a promise to protect rin and her death left him with him a lot of trauma he had so much pain that even though he wasn’t a uchiha, he awakened the mangekyo sharingan. After his teammates died, his sensei died years later. And everyone he ever loved was gone. He had PTSD for years and isolated himself. He went on multiple killing sprees while in the Anbu and build a name for himself as kakashi of the sharingan. Sasuke told kakashi “what if I killed the ones most precious to you” And kakashi told Sasuke “everyone has already been killed” Silencing even Sasuke and making him reconsider his path of hatred. Despite all of this kakashi never turned evil or gave up on the world and never complained
#6 Itachi
Itachi was originally considered a villain who was the murderer of his own clan, but that’s not the entire story. And turns out, it was really his only option. Itachi had to make a decision between his beloved village and his beloved family. Itachi secretly helped the village in getting rid of his own clan who had been plotting a coup. Seeing war as a child he never wanted to see it again. To prevent civil war he choose the village his clan after all his other options were out and as a last resort. After clashing ideology’s with his father, his parents allowed him to kill them and as final words asking him to take care of Sasuke. He had no choice but to kill the girl he loved. His clansmen and his parants. He became a criminal and put in the bingo book and joined the akatsuki as a spy and was hated all for the sake of his village. And Sasuke who he loved the most hated Itachi for years until he learned the truth. And he also lost his best friend shisui which furthered his pain. For the sake of his village and his little brother he was labeled a traitor for life
#7 Obito
Obito like others on the list was an orphan. He was crushed by a rock and had “died” he actually was saved by Madara, who used him and put seal on his heart. He had to recover and gain strength again. Before he could see rin and Kakashi again. He seen him die by the hands of kakashi while running from mist ninja. After seeing his crush die he was in such despair and agony he went berserk and killed everyone and awakened the mangekyo sharingan. He seen how cruel the ninja world was and followed madara’s plan. And started the 4th great ninja war. He was also used by Madara Uchiha who orchestrated his entire downfall and used him for his plans
#8 Kawaki
He had a terrible childhood and was raised by his abusive and drunken father who sold him for money and Jigen became his new abusive adoptive father. He was experimented on and jigen put a karma on him and while dozens of children died he was one of the only survivors. Jigen mistreated him and abused him and put him in danger of dying just to use his body as a vessel and take over his body. Kawaki knew nothing but pain until he met Naruto. And even now Kawaki does not know how to express love properly. You know a characters backstory is sad when Kurama gives them advice
#9 Karin
Karin had a poor life. She seen her mom be used and die right in front of her and had she no time to grieve her loss because she was used and mistreated and she was almost killed the same manner that her mother died. She was abused as a kid and was a war orphan. She was “saved” by orochimaru. Her backstory is anime only but I believe it deserves a mention
#10 Haku
As a kid he had a unique ability. His mother kept her ability from her husband, but when he found out, he got a mob to try to kill them both. Haku's mom died and he had to kill his father and the mob that attacked. He was left an orphan, no one helped him, suicide also crossed his mind. And wondered in the cold, had to fight just for food. And dumpster dive. Then he meets Zabuza Momochi. Who took care of him but made him a weapon and used him as a tool.