For over half a century, Japan has been in darkness. No one can enter or leave the island, except for the elite soldiers of the Skytree: traitors, thieves, and murderers who come only to die facing terrible beings. Captain Neal Kellum made an unforgivable mistake and is now determined to make his death count, but his company's newest recruit, Kiera Amell, is going to make things very difficult for him. She doesn't believe in rules, discipline, or respect for authority; but above all, Kiera is hiding something, and Neal is going to try to discover what it is, even if that means getting close enough to experience emotions he hasn't felt in a long time--dangerous emotions that could doom him again. Empress Echo Akiyama rules over a dying empire and knows desire and passion well, but not love, always distant and unattainable in her position... until Alexa Lalanne appears, having sacrificed everything to meet her, because she has a warning: they are going to destroy her world. The rebel Markel Sagastizabal is the prodigy who could hold the key to breaking the blockade and saving them all, but he has reunited with Kai Inoue, an unscrupulous hitman who knows his weakness well: Kai himself.