This isn't an official anime series despite how professional the art is, today's review is about web light novel series Okashina Futari, but first a bit about the writer Mashiro.
Mashiro is a TG writer, which of course stands for transgender, he produced numerous works on his own website including Kayo-Chan & the sequel Second Chance Hunter Series, Kayo-Chan is about a well dressed little girl who solves problems by transforming the reluctant customer into a girl wearing a fanservice costume, the Hunter series is a taskforce assigned to reverse the process, which is the best I can do with limited translation tools and speaking of translations, another work named Okashina Futari was translated into English by a group of dedicated fans and that is today's review.
Again due to the length of the story as of now not all of it has been translated with only the first 250 chapters translated out of something along the lines of 1500 chapters, if that seems excessive some of the chapters are only something like two sentences long.
The story revolves around a brother & sister who can transform each other into the opposite gender with the power of thought and includes a fanservice costume as well as the rules of the powers are clearly defined through illustration, where when you change gender you must change the clothing to match said gender.
What makes this unique is the way the brother & sister react to the changes; the sister Satori doesn't actually mind being a boy as she believes it to be a challenge where as brother Ayumi is rather uncomfortable about the whole experience as defined below where he's turned into a Chinese Girl.

And it's Ayumi who gets the lead as the story is told from his perspective where many of the transformation scenes are described in great detail throughout the chapters, talking through feelings, describing the unusual feel and design of the clothes, the reactions of the general public and wondering what to do next; Ayumi reluctantly agrees to become Satori's dress-up doll for most of the story, and while it's okay at home, it's not okay in public during one of the most re-posted TG flash of all time where he's transformed into a bride on a public train.
You can find all the translated work on Okashina Futari here along with short stories and another series called BUG. Links to the bride transformation flash is at the bottom, more flash animations on the left side bar which also include a Ballet & Waitress transformation, there's also a gallery of all the pictures which is also at the bottom.
http://castle.midnightaurora.com/mainpage.php?siteID=1&pageID=1&itemID=Okashina_Futari.php
Also I have the link for Okashina Futari's main illustrator Ohyuki.
http://ohyuki.grats.jp/
Ohyuki is a very talented artist who has his own online comic and frequently sends illustrations to Japanese Online RPG sites along with commissioning for Mashiro for Okashina Futari, check out his work, you won't regret it. (Site is in Japanese though)
Final Verdict: Okashina Futari is an interesting read, there aren't many TG story writers who can go into that much detail from a first person perspective and keeps it's audience in until the scene is done and then you do it all again with the next scene but don't expect the translation for this series to be completed in your lifetime, it's already taken 14 years to get this far.