One possible reason could be that Naruto is feeling lonely. Despite having friends, there are times when his past as an orphan and the years of being shunned by the villagers resurfaces, making him feel isolated. Kakashi finding him in such a state might then lead to a heart - to - heart conversation about Naruto's inner struggles.
Maybe he's frustrated about his progress in becoming a stronger ninja. Naruto is always eager to improve and protect his loved ones. If he fails at a particularly difficult training or mission, he might break down in tears. Kakashi, being his sensei, would then offer guidance and motivation.
It could also be related to the loss of someone close. In the Naruto world, there are many battles and sacrifices. If Naruto loses a dear friend or someone he admires, like Jiraiya, the pain might be too much for him to bear and he starts crying. Kakashi would be there to console him and remind him of the importance of moving forward.
Kakashi might immediately offer a comforting presence. He could put his hand on Naruto's shoulder and just be there silently, letting Naruto know he's not alone.
Perhaps he's feeling isolated. Even though he has friends, he often has to face his battles alone in some ways. Ginny finding him crying could be a moment of vulnerability that she witnesses, and it might be related to his feeling of being alone in the fight against the dark forces.
Perhaps he's had a falling - out with his friends. In the Slytherin house, there could be a lot of power dynamics and rivalries. If he's been betrayed by someone he thought was a friend, it would be very upsetting.
The plot might involve Naruto crying due to a misunderstanding with his friends. Kakashi witnesses this and steps in to mediate. He first calms Naruto down and then arranges for Naruto and his friends to have an open conversation. During this process, Kakashi shares some wisdom about friendship and communication, helping them resolve their differences.
One possible reason could be that Naruto is feeling lonely. Despite having friends, he still has moments when the weight of his past, like being an orphan and ostracized in the village as a child, hits him hard. Jiraiya might see Naruto crying because of these memories resurfacing.
One possible fanfiction could be that Kakashi stumbles upon Naruto crying alone in the forest. He sits beside Naruto quietly, not saying a word at first. Then he gently puts his hand on Naruto's shoulder and tells him that it's okay to cry, that showing vulnerability doesn't make him weak. Naruto then pours out his heart about his loneliness and how much he misses his parents. Kakashi listens intently and shares some of his own experiences of loss, creating a deep bond between them in that moment.
It could be the result of Naruto's own inner demons. Maybe he discovers some dark secret about his past, like his parents being involved in something he can't accept. This self - realization could be so traumatic that it makes him cry blood as he struggles to come to terms with it.
Well, it could be that he's feeling the weight of his destiny. Harry has so much on his shoulders, like fighting Voldemort. Maybe he just had a particularly tough encounter with the Dark Arts or lost someone dear in the fight against the dark side. Another reason might be his feeling of isolation. Despite having friends, there are times when he feels alone in his battle.
Their relationship is like a mentor - mentee bond. Kakashi has trained Naruto, and when he sees Naruto achieve great things, it can be overwhelming. For example, when Naruto masters a new jutsu that Kakashi thought was difficult for him, Kakashi might cry out of joy for Naruto's accomplishment.
Maybe she had a bad memory from her past resurface. For example, something related to her time in Mossad or her family issues could have triggered her emotions.