Two short Saa, Koi ni Ochitamae (Fall in love with me) stories and a couple pages related to Fan.
Saa, Koi ni Ochitamae story 1: Noboru and Yuuki explore the sexual side of their relationship. Set after volume 2.
Saa, Koi ni Ochitamae story 2: Noboru wants to avoid Yuuki's phone calls and is being a brat. However the twins just love to talk on the phone! Set after volume 3 - though no spoilers for it.