The No. 1 coveted job: Slut. The next most popular item is tools. Yui volunteers to become a tool, which is also a national qualification.

Yui understands her own sexual tendencies well and decides that she is suited to be a tool. Knowing that being a tool is a tough job, she decided to go to a tool training facility.

At first, she was relieved that the training was easier than she had imagined. But gradually, that leeway is running out.

Yui regrets trying to become a tool so easily, but it's all too late...