ballads - be with you, ashita no kioku, hitomi no naka no galaxy, hero, natsu no namae, aozora pedal, beautiful days.
and that's just a JE pattern. fangirls really just buy singles more than albums because of various reasons. the prices are cheaper and you get multiple versions and stuff. it's hard to explain. irene knows better than me
but that just dosen't happen with arashi. it happens with most johnny's entertainment boy groups.