Rooftop Letters~ A shinkami fanfic

Denki is numb on the outside he's bubbly and electric but when he's alone the mask drops. Sometimes he sits on the roof of UA and just thinks in the quiet. On one of these days, he starts to talk to himself not expecting anyone to hear him but someone does. Denki starts to find notes on the roof addressed to him telling him how special he is, who writes these notes he doesn't know, what he does know is that he's falling in love.