Is there a method to break free from the existence of a background character?

Mobuyama Eiji and Mobuyama Shiro have spent their entire lives as mere "extras" in the narratives of others.

It can't conclude in this manner, can it? There has to be a way to escape! United by a shared ambition, they will do anything that enables them to alter their fate, ANYTHING.

This is the first of a trilogy of interconnected short stories.