Metro Labyrinth: When I Woke Up, I had the Strongest Job, so I Teamed Up with a Chipmunk and Wandered the New World

When Shuu Abe, a 23 year-old hospitalized man, wakes up, he finds himself in a strange underground world rampant with monsters he has never seen before. In front of our puzzled protagonist, appears a talking chipmunk who's a girl(?) called Tamiko. "Mister Hunter, let's squeak on to the surface together!" Says she as the two decide to work together to achieve their goal of escaping the labyrinth...