Itoshiki Mirai ni Kuroi Ken wo

A dark fantasy of intense, heavy obsession clashing in a death-loop world! On his 18th birthday, the third prince Lucas is betrayed by his fiancée, and his personal knight Licht is killed right before his eyes. Overwhelmed by the death of someone precious to him, Lucas screams and cries in heart-wrenching despair... only to sink into the depths of hopelessness. When he opens his eyes again, he finds himself back in the “world before the incident”!? Faced once more with the usual kind Licht, Lucas is flooded with love—but determined not to repeat the same tragedy, he declares that he is dismissing Licht as his personal knight. However, Licht’s eyes suddenly change color as he steals Lucas’s lips and says— “If things were going to turn out like this, I should have made you mine much sooner.” Will Lucas be able to change this tragic future...?

(Source: Manga Updates)