Sekai Saikyou no Honoo Mahoutsukai

Before I knew it, I had become Leonhardt, the fat villainous noble from the game I was obsessed with. But a miserable ending exactly like the game is an absolute no go! Even for my number one favorite, the tragically ill-fated beautiful heroine Celia—if it's me, I'll love her and protect her to the very end, and I'll definitely see us through to a happy ending together! Thanks to the protection of the Great Fire Spirit Ifrit and my efforts since childhood, both my magic and swordsmanship have powered up! Before long, for some reason, I ended up awakening as an unforeseen "Strongest Fire User"! (Source: Hobby Japan, translated)