When Asahi was a young boy, he had a friend named Sakuya who only came out when there was a full moon. One day, she says that she has to leave him, but she gives him a small pendant that she says will protect him in her place. Ten years later, someone with the same name, power and aura as Sakuya saves him - but it's a guy!?

From RebelliousArt:
Risky is an apprentice shinigami who collects souls. Safety is an apprentice angel who saves souls. Due to some accident, Risky and Safety are now magically stuck into one body.