A robotic squid, Kazuya's Doraemon Research Project. It is primitive compared to the cyberdolls. Rena has a fondness for Ikariya, taking it where she goes. It is probable that Ikariya may be the prototype to Kazuya's AI project in which eventually becomes the Maid Program, the core OS of all Cyberdolls. Kazuya make periodical upgrades to Ikariya throughout the anime. With those upgrades, Ikariya gains his own personality.

(Source: Wikipedia)