Tsunade would probably be shocked at first. Naruto is like family to her. She might immediately refuse and try to talk some sense into him. She could say something like 'Naruto, you're stronger than this. There's always a solution to every problem.'
One possible reason could be extreme guilt. Maybe Naruto has done something he believes is unforgivable, like accidentally causing the death of a beloved friend while in a fight. He might think that death is the only way to atone for his mistake.
In some cases, Sasuke could be angry. He might see Naruto's request as a sign of weakness or as Naruto giving up too easily. He could lash out at Naruto, telling him to fight instead of asking for death. However, he would still be deeply troubled by the request and would probably struggle with it for a long time, constantly thinking about whether or not he should consider it.
One possible reason could be that Naruto feels he has become a threat to the village or his friends in some way. Maybe he has some sort of dark power within him that he can't control and he believes Sasuke is the only one strong enough to stop him. Another reason might be related to a prophecy or a greater threat that Naruto thinks his death can prevent, and he trusts Sasuke to carry out this difficult task.
There could also be friends who are so loyal to Naruto that they would consider following his request if they truly believe it's for the greater good. However, they would be deeply pained by it. Kakashi, for instance, might understand Naruto's selfless nature but would also struggle with the moral and emotional implications of taking his life.
She might be initially shocked. Given her own past traumas and her relationship with Naruto, she could be hesitant at first. But then, considering Naruto's lonely situation, she might warm up to the idea and show a more maternal side towards him.
Perhaps he has been through some sort of mental and emotional breakdown. Maybe he has lost too many battles, seen too many friends die, and he feels that he is a burden or that his death would somehow bring peace to his troubled mind. It could also be related to some prophecy or dark secret he has discovered about himself that makes him think death is the best option for everyone.
At first, Naruto would probably be excited. He's always eager to get stronger, so he might see this as an opportunity. He'd trust Tsunade because she's the Hokage and a respected medical ninja. But if the experiments got too painful or started to seem strange, he'd start to question things. He might try to talk to Tsunade about it, but in his Naruto - like way, still be respectful.
Naruto might be longing for a motherly figure in his life. He has always been alone and has seen how others have mothers. Tsunade, being a strong and caring woman in the village, could be someone he looks up to and wishes to have as a mother.
Well, one possible plot could be that after years of fighting side by side and having a deep understanding of each other, Sasuke finally realizes his true feelings for Naruto are more than just friendship. He might plan a very private and special moment to pop the question. Naruto, being the open - hearted person he is, would be initially shocked but then consider it seriously as he also values Sasuke deeply.