Shimmai Tenseisha ni Lv999 Goto Itadakaremashita.

Getting all his levels and first time stolen by an undefeated, cheat-skill-using new adventurer?! Dive into a world where everyone has a special skill. Shu uses his Level 999 ability to save a newly reincarnated salaryman from a magical beast. After returning home and chatting over drinks, the salaryman's skill is revealed—he's a strong, top-tier adventurer with an incredible ability! But the way to activate his skill is only by…?!

"Why don't we level up in bed…?"

(Source: Coolmic)