Z no Jikan

When hardcore FPS enthusiast Hiroaki Dewa pulls off his VR headset and steps outside for the first time in ages, he realizes that the whole world is in ruins! Soon after, he coincidentally runs into horror junkie Otoha Judou, and the two of them team up to endure the zombie apocalypse. One fateful night, a VR AI known as "Raven" leaves them a cryptic message: "Survive, and humanity may flourish once again." Follow these ragtag oddballs as they cling to hope in a hopeless world!

(Source: J-Novel Club)