This is a rather faithful "hot spring situation" work, where the heroine and male lead go to a hot spring together, and end up having to stay in the same room, where their relationship progresses quickly.
The Shigetsuen is an unusual inn, located off the beaten path in a popular hot spring town. Your lover, Miharu Murasaki, has prepared a special one-day plan, full of sex and soothing, just for you.
You boss coerces you into going to dinner with him, and then drugs you...he takes you to a hotel, but in the nick of time, your colleague Ai saves you. However, the drugs have made you hot and bothered, and Ai has taken notice too...