In the present timespace, he is Haruka's classmate and one of the protagonists of the anime. He, unlike other students, is being forced by his mother to go to cram school in order to pass a provincial enrollment test and go to a Tokyo junior high. As a result, he has little time for anything but studying. He initially tries to run away with disastrous results, and later has a blowup with his mother. Once the pressure is relieved, he realizes that he needs to take the exams because he has no special talents.

Yū initially doesn't want anything to do with La'cryma and the Dragon Knights, because of Karasu's contempt for him and Atori's crazed behavior. But he reluctantly gets involved, eventually teaming up with Karasu to save all timespaces – and Haruka – from Noein. When confronted by the monstrous version of himself, he disowns Noein and destroys his power.

(Source: Wikipedia)