Point of information: Most of these Mima-lactation images stem from a meme known as >>301 for short.

http://dic.nicovideo.jp/a/%E3%81%A7%E3%82%82%E9%AD%85%E9%AD%94%E6%A7%98%E3%81%AE%E6%90%BE%E4%B9%B3%E3%81%AA%E3%82%89%E3%81%A1%E3%82%87%E3%81%A3%E3%81%A8%E8%A6%8B%E3%81%9F%E3%81%84%E3%81%8B%E3%82%82

Damn it, I can't read it.
Oh well, time to enjoy the milky ghostly goodness

undinehunt24 said:
Damn it, I can't read it.

>>301 is one of anonymous users on the Livedoor Shitaraba-board topic, ”Hey, does anyone know Mima-sama's whereabouts? (おーい、誰か魅魔様の行方を知らんか？)”
This idiot said a completely off-topic thing on the 301st comment: ”Anyway, I'm interested in milking pics of Mima-sama in some degree. (でも魅魔様の搾乳ならちょっと見たいかも)”
Later, his words became a meme. This is why there are a lot of Mima's milking pics on pixiv.
>>301 is usually described as 8toushin, one of 2ch ascii art characters.

Note that this meme is NOT from 2ch. Livedoor Shitaraba is NHN Japan's 2ch-like Bulletin Board System.