Mushi to Medama Series

Sakaki Guryuu is a multi-talented genius who, despite being gifted and wealthy, decides to teach in the countryside to be together with his lover, Usagawa Rinne, who also happens to be his student. Their peaceful lives are shattered one day when Rinne is killed, in front of Sakaki's eyes, by a girl named "Gankyuu Eguriko," who gouged her eyes out with a spoon. Things take an even stranger turn when Rinne suddenly wakes up as if nothing had happened, and something called an "Eden's Apple" is thrown into the mix.

(Source: Baka-Tsuki)