Well, according to the official site, there are 7 trumpets of Apocalypse. We know 2 (well, 3, because Mika is definitely one, too, we just have yet to see his form; moreover, it was said about him specifically that he is a complete product), that leaves 4 more. Though, I’m not entirely sure if Kimizuki and Youichi will be among the seraphs. Yes, they were experimented on, but with what purpose and to what extent is unknown. In any case, the remaining seraphs are going to be fun for sure, as well as Kimizuki and Youichi’s future developments.