Yuuta Togashi

Age: 15 (S1) 16 (S2) 17 (Movie 2)
Sign: Cancer
Height: 169.8 cm (5'7")
Weight: 60 kg (132 lbs)

A high school boy who used to be a delusional teen, believing himself to be the Dark Flame Master and becoming alienated from everyone as a result. Finding this to be embarrassing, he attempts to erase this past from existence, even choosing to go to a separate high school from all of his junior high school classmates. However, after encountering Rikka, his past delusions come back to haunt him.

As the story goes on, Rikka and Yuuta fall in love eventually creating a "lover's contract" between them, a chuunibyou term they came up with in an attempt to avoid being in a normal relationship..
(Source: Wikipedia)