In this fanfiction, it could be that Naruto's overuse of the Nine - Tails' power has led to some unforeseen consequences. The chakra of the Nine - Tails might be slowly corrupting his body from the inside out. He's keeping it a secret because he doesn't want to lose the trust of the village that has come to rely on his power. He's secretly looking for a way to reverse the damage while still being the strong leader everyone expects him to be.
One possibility could be that Naruto has been poisoned by a new and unknown enemy. This poison is slowly eating away at his life force, and he's trying to hide it from his friends and family so as not to worry them. He might be secretly seeking a cure while still fulfilling his duties as Hokage.
Maybe there's a curse placed on Naruto that is causing him to die secretly. It could be related to some old, forgotten shinobi magic. In the fanfiction, the curse could be slowly draining his chakra and his very essence. He'd be struggling to keep up his normal appearance while he desperately tries to find a way to break the curse.
Chapter 119 is the strongest chapter-level answer because it starts from What is Princess Wen talking about? and follows through on For some reason, he always felt there was a mysteriously calming power....
The best chapter pointer here is Chapter 119, "Wen Jiaojiao is Poisoned!". It opens with What is Princess Wen talking about? and closes on For some reason, he always felt there was a mysteriously calming power....
Chapter 96 is the strongest chapter-level answer because it starts from Jiang Li's words seemed absurd, yet there also seemed to be a trace of... and follows through on Xu Ling couldn't contain her soft sobbing, "How could this happen?.
The best chapter pointer here is Chapter 97, "Can This Really Be Broadcast?". It opens with Suddenly, Jiang Li's livestream room was packed with people, and the... and closes on And you believe what she says?.
A practical answer is Chapter 159, because it turns the idea into a concrete scene. The chapter opens with Seeing the red light of the camera turn on, Su Yinwan looked at the..., adds pressure through The moment the door closed, he straightened his back, and his originally..., and ends on Shang.
If you want the clearest chapter reference, go to Chapter 132. Early on, The new girl in the live-streaming room went crazy.; later, the chapter leans on Who is this handsome guy???" "Ahhh, so handsome, I'm gone, where is the....
If you want the clearest chapter reference, go to Chapter 99. Early on, Seeing the man approach, one of the individuals with a long scar across...; later, the chapter leans on How is it, have those people outside left?" "They're gone." The man spat....
Look to Chapter 109 for the clearest answer. It begins with And another thing," Jiang Li said, taking out a tissue to wipe her lips,..., keeps building through The next time we have a meal, don't try to chat with me unless you're fine..., and lands on [You're indeed more likable than me, the type.
Look to Chapter 149 for the clearest answer. It begins with Seeing that Zhang Cheng's glass was nearly empty, Du Qinglian immediately..., keeps building through Director Zhang, this Zuichun Mountain is a specialty of Bi Garden, brewed..., and lands on Zhang, I introduced myself at the very.
Chapter 113 is the strongest chapter-level answer because it starts from The next day, Jiang Lili was up before dawn as usual. and follows through on If things are really as you say, that is indeed quite serious..