It was announced on the series' official blog that on the fifth and sixth volumes of their BluRay and DVD release, they would include side stories featuring Mini-Ika Musume! Called, Mini-Ika Musume Bangai-hen, the fifth and sixth volumes will be shipped at April 20 and May 18, 2011 respectively.
To those who remembered, she first appeared in the last segment of the fifth episode of the series in which Eiko decides to adopt her, in which we saw a lot of really cute moments of them together! It all turned out it was just a dream by Sanae, the one who is extremely obsessed with Ika Musume.
Source: Ota News Sokuho via ANN, MyAnimeList