Huh? This... wasn't a delusion?

Chuunibyou - it's a self-deprecating term for the somewhat pretentious behavior often seen in second-year middle school students during puberty. By extension, it's become internet slang that ridicules the self-indulgent fantasies and preferences typical of adolescence (see Wikipedia). But here we have a wild case of chuunibyou - Otaku Yaha. He became chuunibyou as a result of elite education from his otaku-inclined parents. After graduating from chuunibyou, Yaha reunites with his dark history notebook and becomes absorbed in nostalgia. However, when he suddenly encounters Lise, an Imagi species, Yaha's story begins. Were the incantations written in the dark history notebook to cast magic actually usable magic? No way, nobody saw it. ...Well, nobody except for one person should have seen it. Didn't you use the [Concealment] incantation? But isn't that just an excuse for it not really being unseen? Huh? Am I being attributed to supernatural phenomena...?