Verb
be a hundred years too early (third-person singular simple present is a hundred years too early, present participle being a hundred years too early, simple past was a hundred years too early, past participle been a hundred years too early)
(idiomatic, anime and manga fandom slang) To be so immature and unprepared as to have no hope of achieving an accomplishment.
Don't make me waste my time! You are a hundred years too early to be an opponent worthy of fighting me!