Makoto's 17-year-old sister (currently 19). Initially she has a rather romantic look on a relationship, and her quest for true love lets her drift through a number of affairs before she finally finds happiness with her first boyfriend, Yosuke. Her experiences and introduction into the sexual world are followed throughout the series. (source: http://en.wikipedia.org/wiki/Futari_Ecchi)
Azusa is Sho's best friend, and she accompanies him through his many travels with the "Superbook"!
Shizuno comes from a wealthy family.
A librarian robot, who produces records of the lost human civilisation related to laughter, setting up the robots' jokes. She acts a bit superior and over-confident.
Me-Mania is one of Mima's biggest fans, to the point where he is totally obsessed with her. When Mima starts to do things that go against his expectations of her, he becomes a stalker believing himself to be led by a "true" Mima.