I found this image in the Mixi application "Kioku-Sketch" as Heus (nuntarou)'s art. Retagged. (Subject: "Free drawing")
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".