So much can change in a single second, and in this one another god was pulled into the human world. In order to maintain balance, there must be an even number in the human world at any given moment, so when a careless person breaks through the barrier and brings something back with them, another appears elsewhere in the world, it's vessel chosen randomly at a time and place to best suit it.
For some reason, even considering the massive damage caused with every summon, the humans just don't seem to learn.
Gravity, Electromagnetism, Strong Force, Weak Force, Soul, and Matter are what they are. But who they will become is anyone's guess.
(BSD fanfiction, I do not own Bungou Stray Dogs, not canonverse compliant, many OCs, OP characters)