Ann Cassandra

Bekku Nanaki is mirror clairvoyant. She moved to Tokyo from the countryside to escape calamities she sees. There she witnesses an accident on the road by a mobile fish vendor who saves her life from being crushed by a billboard from above.

The next day, he turns out to be Banjou Kizaki, her classmate and a student held back due to him being involved in incident and accidents that others attribute to him being unlucky. His eccentric behavior, however, catches her attention which he explains as changing the future...
(Source: Mangaupdates)