Boku to Kimi no Aida ni

Following the wishes from his childhood friend Selma, who passed away in the middle of her dream of escaping from Heaven, a city where everything is artificially controlled, Hawk, a young boy who loves machines, sets out for the outside world. Upon landing in a slave city, Hawk meets a mysterious woman named Dahlia and her companion Sylvain. What will be Hawk's fate in captivity?

(Source: Shueisha, translated)