The protagonists come from the second game "Collar×Malice": Hoshino Ichika and Saeki Yuzuru. Please note that the article contains spoilers for the game.
Hoshino Ichika resigned from the police and went undercover for several years in the organization of his former friend and now enemy Yuzuru Saeki, finally killing him all in one fell swoop.
Sagi Yuzuru was killed by her, and she also died in the bombed base.
Unexpectedly, after their death, the two were resurrected by a mysterious creature calling itself QB, who promised to fulfill one of their wishes as long as they embarked on a journey through various dimensions and worked for them as the price of realizing their wish.
Purpose: Help others and make yourself happy