I'm an S-Rank Demon, and You Want to Be My Wife?

[Everyday sweetness + contract summoning + plot-focused + invincible protagonist + pure love] On his eighteenth birthday, Lin Feiyu made a decision that betrayed his ancestors! After forcibly opening a black box, Lin Feiyu obtained the Grimoire of Summoning. Then, by chance, he successfully summoned his own familiar. But who could have imagined that this familiar would be an S-rank demon? And an astonishingly beautiful young woman, at that! As time passed, though, Lin Feiyu noticed that his familiar was looking at him rather strangely. “Master, I want to be your wife!” “…” And so, a fledgling summoner and his beautiful young familiar began an extraordinary life together.