Dungeon Seekers

Kurase Koryu is a high school boy who spends his days bored. On his way home from high school, he takes a detour and discovers a mysterious QR code on a telephone pole. Curious, he scans it with his smartphone and downloads a certain game app. The name of the app is Dungeon Seekers. Using the camera function, he is able to enter a monster-infested dungeon. ......

(Source: Hifumi Shobo, translated)