Sachiare!

Yotsuba Sachiko is the 25-year-old housewife of an 18-year-old high school boy, Yotsuba Tomoharu. She tries her best to get closer to him and do the things a housewife should do, but their relationship seems to be largely innocent from the beginning.
(Source: MangaHelpers)

Notes:
- Originally serialized on Comic X-Eros under the title Sachiare! (さちあれ！).
- Includes short prologue and epilogue chapters.
- A compilation tankoubon for this series, titled "Shiawase Miman", was published on Dec 31, 2016