That leaves Jin, Rachel, Kokonoe, and Tsubaki.
Actually, I forgot about the 'minor' characters.
Kokonoe...maybe? She just seems too work obsessed, even when she goes crazy with the Golden Tager.
Jin...he's borderline insane (good job, yukianesa) so i dunno if he falls into the category
Tsubaki is all business except when playing around with Noel & co.
Rachel just seems way too indifferent about well, anything.
BB is a great game, but if it does not have the obligatory Tsundere element needed in ALL games nowadays, it will unfortunately have to lose points.