The Sky Crawlers by Ōgai Mori

Set in a world of manufactured, perpetual conflict, the novel follows a young fighter pilot from a class of seemingly ageless pilots who are bred to fight in endless aerial skirmishes; as he moves between missions and relationships, he confronts the monotony and moral cost of a life kept deliberately static by corporations and governments, and the story quietly probes identity, memory, and what it means to be alive when death and change have been abstracted away.