キスは番にひざまずく•Kiss wa Tsugai ni Hizamazuku

Wanton Kisses Are Keys of Sin.

In a world where fated pairs are deemed to be a mere legend, Iori (α) still dreams of finding his destined omega. But when he finally crosses paths with him, it turns out the one he's been longing for is the school's famous "alpha devourer," Leo (Ω), who wants absolutely nothing to do with him. Nevertheless, Iori has no intention of giving up. Is this feeling love, fate, or instinct...? (Source: Overlap, translated)