Ore ga Heroine wo Tasukesugite Sekai ga Little Mokushiroku!?

A boy named Rekka Namidare lives an ordinary life until his sixteenth birthday, when a girl from his future arrives to warn him about an impending interstellar war. He discovers he comes from a bloodline fated for constant conflict. Every time a heroine is in serious danger, Rekka is given an opportunity to rescue her. Over time, the number of girls he saves leads to a future where their intense, jealous affections for him trigger an apocalyptic event.