K.A.A.R.

K.A.A.R. is comprised of material Suehirogari originally released in the Doujinshi series 8 Miles High. It is centered around a middle-school student who discovers that one of his classmates is going without underwear in school, and how she sweeps him up into exhibitionism with her.

Currently has two volumes (Spring Story, 1999, and Summer Story, 2002), but Suehirogari has said he plans on writing two more for a total of four.

Tropes used in K.A.A.R. include:

Biggus Dickus: The shy, effeminate boy (who is in love with the female sidekick... and the main male lead) has a penis that goes down to his knee. We're talking Peter size, here. It's big enough and he's flexible enough that he doesn't need a girlfriend.
Club President: The main characters start up an unofficial club in the second series -- The "Stark Naked Club". Three guesses as to what they're all about.
Cool Big Sis: The student's teacher is fully aware of the games the main male and female lead are playing... and is quite happy to ignore it (when she's not secretly filming them). She even walks in on the main male character "enjoying himself" and just calmly waits for him to finish (he was wearing headphones and had his eyes closed at the time).
Deserted Island: A large part of one of the books revolves around the class having a field trip to one, then the boat owner having a heart attack on the mainland, leaving them stranded. One student goes for help on a makeshift raft, while the others... hang out bored, mostly. Done fairly realistically -- the students have no swimsuits (so they make some out of available materials), clothing damage is a problem since they don't have spare outfits, food is a worry, they have to dig latrines, etc.
Jerk with a Heart of Gold: The fat delinquent turns out to be an ok guy by the end of the series.
Lolicon/Shotacon: The characters are about 4 years younger than his normal protagonists, putting them in middle school. Still, the series has quite a few fans on 2ch -- It's considered his best work by many.
Orphaned Series: The series is supposed to have 4 books. As of this writing, he has only done 2, although his author notes in other books continue to mention his desire to finish this series.
School Newspaper Newshound: Three of them, in fact, who discover the games the main characters are playing and try to, er, expose them.
Tsundere: The main female lead, who upon being caught in a moment of indiscretion, says something so horrific it reduces the main character to a stammering mess. They then start dating. Takahashi would be proud.
Wholesome Crossdresser: Lampshading his own way of drawing faces, the Cute Shotaro Boy main character is a dead ringer for the female sidekick when he has a female wig on. This plays into the climax, when the School Newspaper Newshounds try to expose him for crossdressing with his girlfriend, the female sidekick walks up with a surprise Important Haircut and says, effectively, "Oh hey, yeah, I was at the store with her." The fairly well-hung boy is also seen in drag a few times (it's insinuated he's transgendered or outright gay).