From Wildflower Scans:

When her father is laid off and the family is facing tough times, middle-schooler Kousaka Yayoi selflessly offers to give up her dreams of being a high school student to contribute to the household. Fast forward to a few years later, where Yayoi is about to be given a full-time position at her office job—the only problem is that it requires a high school education! What awaits the 21-year-old high schooler at Hoshinomiya Academy?