Ore to Joushi no Kakushigoto: Tsuzuki no Hanashi

It's been a month since Mikado, an idol otaku worked to the bone by the design company he's employed at, has started dating his superior Anezaki. Even though they've finally gotten consecutive days off, since it feels like they're sex friends as they've just been holed up having sex, he wants to go on a date like normal lovers! Anezaki seems dissatisfied, but then he and Mikado go on a hot springs trip together.
(Source: Kaiohsha, translated)
Note: Includes 2 extra chapters.