Death March to the Parallel World Rhapsody

Ichirou Suzuki, a 30-year-old programmer, finds himself transported to a fantasy RPG world while catching up on sleep. His new surroundings are a mashup of the games he was debugging, and he discovers he's now 17-year-old Satou, a nickname from his beta-testing days. Satou's stats are maxed out to level 310 after he effortlessly wipes out an army of lizardmen with a powerful spell.