That one hits hard. For me, it's gotta be Jiraiya's death scene, no contest. The way it's drawn out over multiple chapters, showing him sinking into the water, thinking about all his failures and Naruto... man. What gets me isn't just the loss itself, but the delayed impact. Naruto finds out while eating shaved ice with Iruka, trying to figure out the code, and it just hits him like a truck. He doesn't even cry at first, just goes numb and walks away with the popsicle dripping down his hand. It's brutal because it's not a flashy battlefield send-off; it's quiet, mundane, and utterly devastating. The silence in those panels is louder than any explosion.
I think it's the saddest because it feels so preventable, yet so inevitable. Jiraiya died doing what he believed was right, gathering intel, but he died alone. And Naruto never got to show him how far he'd come, never got that final proud nod. The entire 'Tale of Jiraiya the Gallant' motif just twists the knife. It's not just a character dying; it's the death of a certain kind of hope and mentorship for Naruto, and the series never really fills that void in the same way.