Watashi no Messiah-sama

Shinya doesn't get stellar grades, he's not athletic, he's a coward, he's a wimp...he's a general good-for-nothing. One day, however; he meets Haruna. A girl that could change his life forever. Haruna tells Shinya he is the Messiah. The Lord chosen to save her world and that she is his shield. Could it be true? Could Shinya's life of ineptitude be balance for this one grand cause? Is he really the Messiah? If he is, can he save himself, let alone an entire world?