Natsuki, an office lady who had been having an affair with her boss for 10 years, got married to a colleague last month and is planning to retire next month. She is going on a business trip to a local client, and takes her boss on a final trip to a hot spring. In the past, she even thought about marrying her boss. For 10 years, the two have been carrying on their relationship without the company or her boss's wife finding out, and up until now, they have only had sex with condoms. She wants to do it raw one last time... On what may be her last creampie affair trip, she wants her boss's sperm...