イカ娘」 by (六尺猫)

According to the obi strip found on the 13th volume, Anbe Masahiro’s supernatural-comedy series, 「Shinryaku! Ika Musume」 (侵略!!イカ娘), will be receiving a new OAD on June 7th. It will be bundled with the limited-edition 14th volume of the manga.

The first OAD was released on August 8th, 2012. It was bundled with the LE 12th manga volume.

*OAD #1 OP:

[Source]