The Earth is on the brink of destruction, and Nymph and Astraea have fallen one after another... To save the world, the last remaining Ikaros takes Sakurai Tomoki to the sky city—Synapse. In the beautiful sky, Ikaros recalls the past... Every day, every minute, every second spent with her master was filled with happiness... The burning Ikaros and Sakurai Tomoki—what will their final fate be...?