Crossover: This Is a Proper Shojo Manga

He woke up one morning and found an egg in his bed. Niwa Ikuto, sitting on top of the egg, felt like he was hatching a chick. Quite literally: An egg with dark red markings. It cracked open. A tiny, pitch-black thing hatched out. "Who's tiny? Remember, my name is Nakahara Chuuya. Say that again, and I'll crush you with gravity!" "Are you my Guardian Character?" "...Huh?" This story plays around with the Guardian Character setup + [unintelligible] and so on, mm-hmm (?) It involves all kinds of old-school girls' and boys' manga (?!) There'll be more than one Guardian Character. After all, even a harem protagonist needs multiple eggs. Not sure if there'll be a couple, but given the author's style, romance will be difficult. Theme: The story of a cute boy growing into a strong, dependable man.