Gaishuu Isshoku Ch 50 'link' -

Yuki looks at him. “I want to see the sun set again. Even if it hurts.”

“Don’t look at the sky,” she whispers. gaishuu isshoku ch 50

It seems you're referring to (possibly a manga or light novel series), specifically looking for a story related to Chapter 50 . However, as of my current knowledge cutoff, there is no widely known or officially translated series by that exact title in mainstream manga databases. Yuki looks at him

Now, in Chapter 50, Kaito must make a choice. He has found the — a shard of pure, burning red hidden beneath the old art school. If he shatters it, the color will return — but so will pain, war, and imperfection. It seems you're referring to (possibly a manga

was one of the last. His left eye still held a fleck of amber. He hid in the subway tunnels beneath the eastern ward, where the Color Eaters — slender, faceless things that moved like spilled ink — hadn't yet reached.

Kaito raises the shard. The great grey eclipse trembles.

It started as a rumor. A patch of grey on a shop sign. Then a whole building. Then a block. Now, Hazakura was a charcoal sketch of itself. People’s clothes, faces, even their eyes — drained into monotone. Only a few still remembered red.