Meikyuu Metro: Mezametara Saikyou Shoku Datta node Shimarisu wo Tsurete Shinsekai wo Aruku

When Abe Shuu who just started working opened his eyes, what he saw in front of him was a completely changed scenery, Tokyo 100 years in the future... Even worse, he is at the 50th underground floor of the Ootsuka Metro, which is like a maze completely overrun by monsters. Wandering around, not knowing where to go he came across a very talkative female chipmunk, Tamiko! Now he is aiming to reach the end of the maze with his cute newly found partner Tamiko! And although he is only level 1, he has the immortality skill so he is aiming to become the strongest! .. Which would be impossible with just one person.. but with one person and one animal friend it should be possible! The adventure of the weakest hunter with the strongest skill and a cute magical beast starts now!!

(Source: HJ Novels, translated)