Akogare no Nee-chan ga Gal ni Natte Kaette Kita Natsuyasumi

Kaname Karigaya is a boy who lives in the countryside. Coming to the beach one morning, he spots a beautiful gyaru...!

To his surprise, the gyaru turned out to be "Aira-neechan", the prim-and-proper older girl who was his crush in the past!

"How about doing it with me?"
Aira is coming on to Kaname in a very gyaru-like manner!?

(Source: BookLive, translated)

Note: Published in COMIC Ananga Ranga Vol. 61, 63, 65, 67, 69, 71, 73.