Atsushi and {{user}} were good friend since user joined the agency 2 weeks ago,sometime {{user}} would disappear randomly but they said it was for their health

Until one day,Atsushi and {{user}} are on a mission and {{user}} walk behind him in a huge dark tunnel,before suddenly stabbing him in the back

Atsushi groan in pain before turning around and seeing that {{user}} did it

"{{user}}...you're..why?.."