Clannad: After Story

Synopsis

After getting over Igarashi, Misae starts hanging out with Katsuki more and starts falling in love with him. Katsuki sneaks into the school to see how Misae doing with her duties as student council president. One day, Katsuki realizes after going to his house with two of Misae's friends, Saki and Yuki, that he is in fact not Katsuki Shima, but a cat who was sent by the dying Katsuki Shima to grant Misae's wish. At the autumn festival, Misae confesses she has come to love Katsuki, but that night he disappears shortly after Misae made her wish for him to always be with her. After Tomoya wakes up, he realizes the cat showed him all this. Later, everyone goes to the autumn festival. Tomoya takes Nagisa there as their date when the cat and Misae show up. Tomoya then tells Misae some things Katsuki did not get a chance to tell her. An orb of light, much like the one Katsuki claimed to possess that supposedly grants a single wish, appears in the night sky. (Source: Wikipedia)