There's Fanfiction About Us?

It's the fifth anniversary of Rui Tachibana starting his career as a pop star. The girls love his younger bandmate, Hibiki Shinjo, because he's a man of few words and is very aloof, but he normally delights in bugging Rui. Their manager thinks it's sweet, like Hibiki's a little kid... Since Hibiki has a hard time getting up in the mornings, he sleeps over at Rui's one night before an early photoshoot. While Rui is taking a bath, Hibiki does an internet search for their names... even though they've been warned against doing just that. They find a very suspicious-looking, password-protected website, and they can't believe what they see!! In this fan-created manga, the two of them get up to such naughty things...! Rui's imagination starts running wild, and Hibiki makes a suggestion...

(Source: Brite Publishing)

Note: Includes two extra chapters.