I wasn't sure if anybody has his official site or not, but I finally found it. Here's some links:
Mentaiko's official website:
http://menntaiko.sakura.ne.jp/top.html
An online store where you can purchase his doujinshi:
http://eng.dlsite.com/fsr/=/kw/RG10680/target_site/1 (This is in English, and I believe they ship to the USA, and Canada)
Also just some personal thoughts: If you guys love Mentaiko like I do, then I recommend purchasing copies of your favourite doujinshis from there. I've recently read the first 3 parts of "Itai Itai Itai", and I love it. I'm waiting for part 4, and hopefully it'll come out soon. My point is that doujinshi artists aren't as accomplished as manga-ka, so they need the support of their fans. Why purchase a doujinshi I can't read when I have the translation here? That's fine, but a hard copy of it can help further the work of Mentaiko, and continue reading the translations on here.
Also it seems he hasn't finished making Part 4 of "Itai Itai itai". So just be a little more patient I guess
P.S. If you can't read the website(obviously), just enter the URL on google.com/translate or use Google Chrome.
Comments are appreciated
