kleine kopfrechenübung, pi mal daumen 8.5k stunden pro jahr, mal 3600 sekunden pro stunde ca 30millionen sekunden im jahr, also grob genauso viel herzschläge, mal ca 100 jahre lebensdauer sind das ca 3 milliarden, nicht billionen
bit of a tightrope walk between him being an asshole idealising being a bully and him just being an insecure kid (especially since his sister probably administers him hrt(at minimum puberty blockers) against his will).
in the first sleepover chapter we see nagi having had a previous experience with someone that felt a bit belittling so she's probably pushing herself to act more 'mature'. which i think is why we see nagi be more of a driving force with action while manatsu is stepping on the gas with emotion...