The Heartthrob System cultivates brotherhood online

System 004 wanted to join Long Aotian's department, but the director thought he didn't understand brotherhood. So the director sent him to several small worlds to gain experience and feel what a real brother is. However, Ling Si's brother identity was not right, and the protagonist and supporting characters didn't seem to want to be brothers with him... World 4: The cannon fodder of the Demon Lord (?) World 004: The bodyguard of the evil fake master (?) World [-]: The transparent roommate of Long Aotian in the end of the world (?) World [-]: The cannon fodder of the aristocratic college f[-] A (ing) World [-]: The staff of the prince in the cold palace [-] is Ling Si, a system that doesn't understand any emotions, but...