According to here, 1st volume sold about 53,000 units so far. Not surprising, considering the critical acclaim it got during airing few weeks ago. SHAFT has land another goldmine besides Bakemonogatari.
Congrats. This is what Yamamoto Yutaka wanted with Fractale but failed with pretty low volume of 830 plus on April 2011 sales. In contrast, the harem mecha anime Infinite Stratos did 35,000 units so far. Pretty good indicator for 2nd season possibility.
Some pundits will flail hands in air, saying Japanese anime fans have gone moe mad.
anime