Futari No Tame Ni Sekai Wa Aru Noふたりのために世界はあるの; 水城せとな傑作集2 ふたりのために世界はあるの; The Queen's Favorite; The World Exists Because of the Two of Us; The World Exists for Just Us Two; Valentine Cinema

From ShoujoMagic: 1) Futari no Tame ni Sekai wa Aru no (2 chapters and an extra) Asukagawa Chiharu is student body president of Ushitora High. Kisaragi Kyou is student body president of Ushitora's rival school, Bishin Academy. That naturally makes Chiharu and Kyou bitter rivals as well, but the relationship they hesitate to flaunt in front of the public eye is one of... lovers! They even have sex at hotels and are an average (!?) couple!! See "Soko wa Nemuri no Mori," story 02 : "The Star Knows Everything", for a side story of this manga. 2) Valentine Cinema 3) The Queen's Favorite