Japanese Title: 初めてのオナホえっち。
URL: http://www.soranini.com/work/cg10/06.html

One of sample scenes of a doujin image collection 魔法のオナホ 妹編 (Mahou no Onaho Imouto Hen) by Katase Aoko.
It was originally posted on pixiv (pixiv #46401074).