Game Kaishi Mae ni Shinu Mob Akuyaku Ouji ni Tensei shita Ore: Oshi Heroine no Imouto to Shiawase ni Naru Tame ni Saijaku Mahou "Dark Edge" wo Kajou na Doryoku de Kiwamenuitara, Saikyou no Bukkoware Seinou to Kashiteita Ken

I Reincarnated as a Mob Villain Prince Who Dies Before the Game Even Starts: In Order to Be Happy with My Favorite Heroine's Sister, I Excessively Mastered the Weakest Magic, [Dark Blade], and It Ended Up Becoming the Strongest, Most Broken Magic