Izumi is 21 years old. She has been working hard every day. One day, an owner of a host club appears in front of her and offers her to be a planning adviser of his new host club. It is a well-paid offer, but there is one big problem.... She has never visited a host club. "I have to check it by myself!" Like this, she opens the door of a famous host club, "Club Katze". There, a sweet and beautiful world she has never experienced awaits her.... She gradually gets addicted to the world....