A tweet by MAPPA confirms that the boy in the first pv is the protagonist and that his name is Kazuki Yasaka [矢逆 一稀]. His seiyuu hasn’t been announced yet but it sounds like Ayumu Murase. He’s the voice of Rui Ninomiya in Gatchaman Crowds, Ryo Asuka in Devilman Crybaby and Shoyo Hinata in Haikyuu!!