Maybe he'd meet some old enemies who have been locked up there. They might try to take revenge on him. But Naruto being Naruto, he would not be afraid and would face them head - on. Also, there could be some characters who were wrongly imprisoned and would become his allies.
In fanfiction, Naruto sent to Hozuki Castle might encounter some mysterious inmates. There could be shinobi from other villages who have their own stories and grudges. These encounters could lead to interesting plot developments. For example, they might share knowledge about different jutsu or tell him about hidden secrets in the ninja world that he didn't know before.
He could meet some powerful criminals. These could be people with unique and dangerous abilities that Naruto has never encountered before.
He might face some really tough opponents. In the Naruto world, Hozuki Castle is known for being a dangerous place. Naruto would probably use his signature jutsu like Rasengan to defend himself. Maybe he'd also try to make allies among the inmates there.
One common theme is mystery. The Hozuki Castle is often depicted as a place full of secrets waiting to be uncovered. Another theme is power. There might be powerful jutsus or artifacts hidden within the castle that the characters seek.
Perhaps Naruto discovers a dark secret about Hozuki Castle that the rulers don't want to be known. In an attempt to expose it, they turn the tables on him and make it seem like he's the one betraying the castle. This could lead to Naruto having to fight not only the castle's forces but also his former friends who have been misled.
In the 'Naruto leaves after Hozuki Castle' fanfiction, he could be leaving because he's completed a mission there. He might be leaving behind some sort of mystery or unfinished business. Perhaps there was a powerful item or secret at Hozuki Castle that Naruto either uncovered or was unable to fully understand, and his leaving is to seek more knowledge or help regarding it.
Well, there's 'The Enigma of Hozuki Castle in Naruto'. This fanfiction is quite unique as it combines elements of mystery and action. The story revolves around a group of ninjas trying to solve the mystery of a strange energy source located deep within Hozuki Castle. They encounter many foes and obstacles along the way, making it a very exciting read.
He would most likely meet his father, Minato Namikaze, and his mother, Kushina Uzumaki. These are the two main family members he never really got to know growing up.
Sakura would be heartbroken. She's always seen Naruto as a dear friend. But she also has a strong sense of justice. So she would be conflicted, wanting to believe Naruto is innocent but also being influenced by the evidence against him.
In the fanfiction, Naruto could leave Hozuki Castle because he feels out of place there. Despite his friendly nature, the culture or the people in the castle might be too different from what he's used to. He might long for the familiar environment of Konoha or his friends, and this homesickness drives him to leave, even if there were unfinished tasks at the castle. His departure could then lead to a journey of self - discovery as he tries to figure out where he truly belongs in the ninja world.
He might meet the samurai of Iron Country. These are warriors with different fighting styles compared to the ninjas. Naruto could learn a great deal from them, like their swordsmanship or their sense of honor.
He could meet the Nords. They are a tough and hardy race, and Harry might learn a thing or two from them about survival in the harsh northern regions of Tamriel.