From Nagareboshi Manga:
Aria’s parents have been gone since she was very young. Thus, she’s had to grow up in a “foster home” of sorts, and was raised by nuns. On her 16th birthday, Aria recieves a present in the mail– a ring from her “Daddy-long-legs” (a man who protects someone from afar while they’re growing up)! All of a sudden Aria’s life is thrown into chaos. Men try to run her over with cars, shoot her, and kidnap her. Relief comes in the form of Canon, who claims he’s her bodyguard. But can he keep Aria safe forever?