That's John-K-Peeta, I am pretty sure it had made other similar chapters, is that the one where the girl breaks the window on a game and goes to search for a ball?. Now that I remember there was that clean pipe story, I think it was called Yumiko-chan vs Nazo Kamen, I believe I posted it in the Flame & Bullshit section, it was an omage to Henmaru Machino (I wonder if the mushroom story was as well).
[Koume Keito] Kafun Shoujo Chuuihou! [2006-11-20(2006-11-30)]
http://www.megaupload.com/?d=GU6E684J
I had the title of this chapter, I don't remember now how was it called.
Also attached below.
[Nakano Yuuki(中野友貴)] Tenshi no Otearai (天使のお手洗い)[2005-11]
[Nakano Yuuki(中野友貴)] EcoMo (エコモ)[2005-10]
Both authors are currently inactive, at least Koume isn't making hentai to my knowledge.
Pretty much the authors Shishi sonson mentioned have done a story like this at some point, there were likely more but hardly any really I remember interesting Hiroyoshi Kira is one of the best examples the stories seem rather funny in comparisong to other authors, like the one from Koume Keito. There is then all the futanari content which has been posted to no end, maybe HG Chagawa made and story not involving futanari with this content, but I am not sure.
SECRET JOURNEY already ended by the way on Chapter 07 (counting starts from chapter 00).
[Giyuugun(戯遊群)] Aya-chan Graffiti (あやちゃんグラフィティ)[1994-02-15]
http://www.megaupload.com/?d=AIE25IPH
One of the long lost authors, sort of, it used to have works serialized on the D-Cup anthologies if I am not mistaken the story extends for a few chapters, it did another similar single chapter but not like this.
