Manga wo Yomeru Ore ga Sekai Saikyou: Yome-tachi to Sugosu Kimama na Seikatsu

I was reincarnated into a world where you learn to use magic by reading grimoires. And these magic grimoires' contents are.. You wouldn’t believe it, but they look like manga. The people in this world would normally take about a year to finish reading one grimoire. But for me, it's like reading a manga, which would take me less than an hour. Interpreting and understanding all kinds of grimoires allowed the six-year old me to quickly became the world’s strongest mage. That was also when I met my bride-to-be, also six years old, and we started living a carefree life!

(Source: GA Bunko, translated)