Love Kiss! Anchor ~Anata no Kiss de Tsukamaete~

One day after the last class on the school I met a girl, Nano, and by an accident we kissed. "Your kiss sealed me in this world!" She said and my peaceful days came to an end. After that Nano was with me everywhere I go. Suddenly all the girls around me; my childhood friends, even my sister Chisa started to act much closer towards me. Is it jealousy? Knowing that if I don't kiss her again Nano would disappear from this world I started dating her, but is it right thing to do to the others? What if it isn't enough and Nano still leaves?