Gokuaku Kizoku, Kenkyo Kenjitsu ni Musou suru: Gensaku Chishiki to Koyuu Mahou "Kokuu" wo Kushi shite, Hametsu End wo Kaihi shimasu

One day, a hardcore completionist of the incredibly complex, multi-ending RPG Ronzorkia finds himself reincarnated into the game's world. Worse yet, he has been reborn as Hollow von Heisenberg... a lazy, arrogant villain fated to die in absolutely every route. "If I don't change things, the game's 'scenario' is going to murder me...!" There is only one way to survive. He must weaponize the exhaustive game knowledge from his past life, completely master Hollow's unique magic, and become the most overpowered existence in this world. His first step? It's becoming the apprentice of his master swordsman butler... (Source: Kadokawa, translated)