I Have a Crush on Someone Else's Guide

Loving another person may not be a crime, but there are some people one simply must not love. Clergy are such people, as are those who are married. And, there is one more. Guides are also such people. Or rather, I should add a modifier: *someone else's* Guide. -Citizens, this is an actual emergency. A Red Alert has been issued. Please stop what you are doing immediately and evacuate to a safe location to avoid the creatures. Repeating, this is a Red Alert. In a world overrun by a virus that turns humans into creatures, we live in this apocalypse relying on a half-baked vaccine. The side effect of the vaccine is the manifestation of Espers. Even after receiving the vaccine, the unlucky ones...