Artist's commentary:

Title: 背中が煤けてますよ
この絵を一度見たことある方がおられるかも知れませんが、Pixivに以前ＵＰされてたものは無断で転載されたものであり、オリジナルはmixiの記憶スケッチで私が投稿したものです。
時間がなくて未完成でＵＰしたため、その後コツコツとローカルで修正してたんですが、まさかその間に他人の絵にされてたとは思いもよらず･･･。というわけで自分なりの完成版がようやく出来上がりましたので、改めてＵＰさせていただきます（改めてってか自分的には初ＵＰなんですがｗ）。
ミクさんなんだからやっぱ緑一色デスヨネー。

Artist's commentary:

Title: 'Your back is dingy.' ('Naki no Ryuu' reference.)
I think some of you have already seen this drawing before, but the one which was uploaded on the Pixiv formerly was reproduced without permission by someone else, and the original one was posted by me on the Mixi application "Kioku-Sketch".
Since I did not have enough time, I uploaded without having completed it, so after that I have been modifying the image little by little which I had saved locally, but I have never imagined that meanwhile somebody else made it his/her drawing.... Therefore, since I have completed my finished version, I am going to upload it again (well, for me, this is the first time to upload, so it is not "again" lol)
'Ryyyiisoo (All green)' is an indispensable yaku for Miku, isn't it?

Mixi application is something similar to Facebook application.
"記憶スケッチ (Kioku / memory -Sketch)" is an oekaki board application where you can post your drawings made with 2D drawing applet.
This application was made aiming at "enjoying unskilled drawings made with a vague memory".

I like where this is going.

This isn't "just" Ryuu-ii-sou. It's also Suu-an-kou Tanki; worth triple yakuman in total by certain rules.

For some reason, I'm more interested how the game is missing a north and south wall while the east and west wall are still intact