Xam’d: Lost Memories (2008) IMDb
A 1940s-style bus full of high-school students on a mostly demilitarized vassal island is blown up in an apparent terrorist act against its empire. A weird piece of shrapnel from the explosion is embedded in one of the students. He has been xam’d and will now turn into a biometallic monster from time to time. It’s not too bad. Pretty soon, he’s helping out on an airship, delivering the mail.
Epic SF-fantasy by Bones. It seems to be aimed at a relatively general audience, considering its genre. It is a mediocre mix of Miyazaki-like motifs—mostly Nausicaä (1984) and Castle in the Sky (1986)—and a family-friendly epic of war and madness, with the inherent body horror of the premise toned way down. It’s mostly shallow and poorly focused, but surprisingly, a few of the high-schoolers’ parents are developed characters, and fan-service levels are low, so it’s not a parade of stereotypes.
References here: Children Who Chase Lost Voices (2011).