Per Wiki:

Mimasaka is arguably the kindest and most mature member of F4. His family is very powerful in the Japanese underground (in the manga they own a large trading company). He keeps his cool and rarely loses his temper, although when he does, even Domyoji has to run for the hills. Akira is the other of the group's two playboys. His tastes tend towards older women, mainly because of his mother's childish ways. He has two younger sisters who are twins. He is also the one F4 member who like to and only uses cash. It was revealed in a special chapter that he actually had romantic feelings for Tsukushi, as she sees him as the man that he is, and sincerely appreciates him for it. Tsukushi also makes him realize that since he helps balance F4 out, a supporter if you will, that if he ever leaves them, the F4 will fall apart. However, he keeps his feelings to himself, due to the fact he cherishes his friendship with Tsukasa.....He also often joins Sojiroh in teasing Tsukasa about being a virgin.