God has been dead for some time, and the angels in heaven have decided it is time to find a replacement. Though very reluctant, the angel Rain has been chosen as one of the four candidates in for consideration to become the next God. He and the four other candidates will decend to earth for one year so that they may perform a test to determine their suitability for the position, with the ability to reveal their true identity to one human being of earth.
Thus, Natsume Shirou, a very normal high schooler with dreams of becoming a teacher, is chosen by the angel Rain to be the help. As for the test, Rain and Shirou must raise a 'baby', with no thoughts or emotions of its own, into a creature as close to a human as possible.