If you're looking for manga similar to AR: Forgotten summer, you might like these titles.
A romantic comedy about three guys, part-time worker Chitose Shusuke, the cool, handsome illustrator Otori Kakeru, and the lecherous 35-year-old owner of the bar/cafe where they hang out, Karube Karuo. They flirt with the waitresses, forceful college student Eriko and repeating college entrance examinee Kinako. Soon Chitose will meet a cute young author who is going to become a part of his life...
It’s summer vacation and Keiichi’s parents left him with his five younger sisters to go on an overseas trip. Now with their parents far out of the picture, his younger sisters are aggressively making their moves on him. Of course there’s no way he can hold back.
Taking place approximately 50 years after the original D.C. - Da Capo - series, the story revolves around Sakurai Yoshiyuki and Otome & Yume, the two granddaughters of the original D.C. - Da Capo protagonists Junichi and Nemu.