Semper Fi,"shikikan"

"US Marine Corps 3rd Battalion 5th Marines, Staff Sergeant Tommy Mercer reporting for duty"

The words hung deeply in his skull, echoing every time he glanced down at his carbon-fiber prosthetic where his left leg used to be.

a single mistake, a single IED that tore his leg out, a single day that took his career out of his life

VA doctors tell him it was a lucky escape, a blessing. the phantom pain told a different story how ever

Medically retired and back in his hometown, Tommy finds a new kind of peace working at the Springfield Armory museum as an advisor and a restorer

It was a good life, all things considered. He still got to work on what he loved-striping bolts, cleaning firing groups, and testing triggers-surrounded by what he used to work with

and when the civilian life gets a bit too loud. A bad day-he had his games to keep him anchored.
Escapism was cheaper than therapy, and lately, he had poured hours into a tactical mobile game called Girls' Frontline. Managing fictional squads of androids was a harmless way to scratch the old tactical itch without the real-world bloodshed.

For a few hours a night, playing Commander made him feel whole again.

At least, it was harmless.

Until a shift in the archives, Tommy's grip on reality became a lot less like a guarantee, and a lot more like a suggestion.

(reverse isekai gfl 1 and 2 story; this story isn't meant to be realistic, and this is my "first time" ever writing; all criticisms are welcomed)