Karen's finally arrived at her place of destiny!" To become a great maid like her grandmother, our main character Karen Otonashi, passes the test to become a maid at the Mitsurugi home! But, the Mitsurugi home is different from how she remembers it, and a shadowy figure follows her as she uncovers the mystery. The birthday party for the youngest Mitsurugi son, Rei, is attended by celebrities from various countries. At the party, Karen struggles with a series of mishaps. And when her Kazumasa shows up in the nick of time... In this party, Karen finds an important hidden purpose...