Isurugi Ouji and Shinkawa Ru have a special kind of relationship. Not only are they childhood friends, their relationship will make or break society. Ru is a psychotic murderer who uses her long nails, which she hides by wearing gloves, to rip through people. If Ru feels that she dislikes a person, she will go on a rampage, killing them and anyone in the vicinity. The only thing holding her back is Ouji, who she has a crush on. It is up to Ouji if Ru will use her rage for hunting down other serial killers or turn into an unstoppable evil.