Zoku Oku-sama wa Onee-chan!?

Toshiya and Yukari have been a married couple for a year but are not experiencing peaceful days as the wife, Yukari, is passionately studying new sexual techniques to spice up their love life. Meanwhile, they have the added complication of Yukari's sister-in-law, Kaori, moving in and behaving very freely, trying to initiate sexual activity. In addition, a new classmate of the husband, Tomomi, is showing a keen interest in him. Other characters, such as Yukari's mother Masae and classmates, also provide comedic moments and advices. Will they be able to maintain their happiness amidst these challenges?