Siren wa Kimi ni Utawanai

Kanoha Takanashi is a descendent of Sirens and is infatuated with her classmate, Kei Shibuya. Torn between her feelings and the Siren's unique nature of yearning to eat the one they love, Kanoha musters up the courage to confess to him—only to get completely rejected on the spot! But what happens when she finds out Shibuya-kun's secret...?

(Source: MANGA Plus)