Ebina Tsukushi was just a normal high school guy who didn't stand out in his class at all. He wished that - despite being distanced from his childhood friend Fujikawa Himawari - he would have hope for his love life in the future. But even when he tried inviting her to walk together from school, she only told him that "It would be embarrassing if there was rumors spread about us being close," slightly crumbling his heart. Even when he confessed to her, he got utterly shot down and became very depressed. However, on that same day he got rejected, his very confident and popular older sister Nadeshiko, who had been studying abroad, returned home! Wanting to be as confident as she was and live a fulfilling high school life, Nadeshiko, who was also huge brocon, just told him: "Leave it all to me!" A couple of days later, he found out that she had planned something up together with the school's haraguro nurse, Ayame -- With the power of his big and powerful cock, he would conquer the hearts of his schoolmates (including a teacher's) and create himself a harem. With the help of both Nadeshiko and Ayame, Tsukushi's unexpected harem life began!

過保護な姉の「茜」と妹の「橙香」に囲まれ生活してきた主人公「晴海虹」。 このままではダメ人間になってしまうと、密かに想いをよせる幼馴染「豊洲藍子」に告白するがあえなく玉砕。 彼女に振り向いて欲しくて、彼女の憧れである姉の「碧」を超えようと生徒会選挙に立候補する。 しかし、嫉妬したクラスの女子「月島白亜」の妨害でトラウマものの事件が発生。 演説会で全校生徒を前に熱弁をふるっている最中、白亜に足をかけられた「竹芝浅黄」がつんのめり虹の元へ…… そして、ズボンを引きおろされチ○コを丸出しさせられてしまう! ! もう、俺の人生はオワタと思い悩むのだったが次の日から――男子からは敬語でうやまわれ、 一部の女子からは羨望のまなざしで見られ、妹の親友であり学園のアイドル「品川黒子」は大金持ちの財力をいかし何かと贈り物をしてくるし、ドS転校生の「スカーレット・ウェルヘルミナカーデ」にはペットにしてあげると迫まられ、風紀に厳しい担任の「芝浦桜」のみならず、ヒステリックな理事長の「辰巳紫陽花」すらいつもと違う目でみているような…? 虹を過保護に扱う姉妹と女子達の欲望が渦巻く、人生逆転チ○コ無双ストーリー!! 「女なんてつっこんじゃえば、何でも言うことなんて聞くもんよ! 」(姉談) 憧れの彼女は虹をどう想っているのか!?