Tomoki Sakurai's peaceful life is now long in the past, because he has to deal with two angeloids, Ikaros and Nymph, as well as with his friends from school, all of whom are very special in their own ways. Tomoki's recurring dream about an angel warning him from the rage of heavens is becoming very common, until one day a new angel, who is as powerful as Ikaros, arrives Earth with the sole purpose of terminating Tomoki—his dream is starting to connect both realities, the Earth and the Synapses.

Tomoki Sakurai often encounters a strange girl in his dreams asking for his help, but he can't remember her face when he wakes up. When an Unidentified Mysterious Animal (U.M.A.) falls out of the sky, his life of pacifism suddenly becomes complicated. The animal turns out to be an angel, Ikaros.

Season 0 of House of the Dragon premiered on September 9, 2010.