Strawberry Sitters

Ringo Morikawa lives with her hardworking mother and younger sister Mikan. To help her mom who is often ill, Ringo acts as a mother to Mikan. When their mother is hospitalized, Mikan is sent to the nanny agency Ichigo Group, which is run by none other than Ringo's classmate Kei, the most popular guy in school. The Ichigo Group is often in trouble, but Kei is always there to help Ringo and her friends out, and as a result, their relationship gradually deepens.

(Source: Shogakukan, translated)

Included one-shots:
Volume 1: Lingerie Logic, Lingerie Logic: Version Pink
Volume 2: Shitteru Kimochi, Shiranai Karada