" Can't I go 1 week without getting sick?! "
He is vulnerable to illness, which is why he hates unsanitary places because it can cause him to become sick. When he's sick he gets stressed easily, since it prevents him to work on his research. So he frequently fidget with his ears to calm down, because they're soft.
" Merah, Jingga, Kuning, Hijau, Biru, Nila, Ungu "
His name "Mejiku Hibiniu" derives from Indonesian language and is an abbreviation of the rainbow colors.