He jabbed his palm into the center of the girl’s chest.
What looked like a stake made of light shot forcefully out.
“I will turn you into a fairy.”
Time stopped.
The explosions disappeared.
In that silent space, Magic God Othinus’s eye was opened wide. Only Ollerus’s words filled the stillness of Sargasso.
“I built a spell out of a historical fact the great Christian powers carried out without realizing it. Simply put, they shrank down the pagan gods. The king of the forest transformed into a dwarf. The queen of the sea was remade into a female monster that sank ships. The god that is hit by this spell will be dragged down from the territory of a magic god and forcibly returned to the territory of a human!!”
One theory said the gods of the many old religions that conflicted with Christianity were reclassified as evil gods who fell under the category of demons. Those became clear enemies, but there were others that had been remade into beings that lived alongside mankind.
In other words, fairies.

Toaru Majutsu no Index New Testament vol.8 epilogue