Tako Luka (たこルカ) is an officially recognized derivative, she had a very important involvement in the Vocaloid fandom, most notably in the Japanese community. The term "Derivative" is used here to describe a fanmade Vocaloid character that is based on an already existing character.
Tako Luka is the indirect result of the Character Item War that was made to determine Luka's character item. Tako Luka was created by Sangatsu Youka (三月八日), aka. Sanpachi, after realizing Luka's hair reminded him of an octopus. Her creation marked the end of the cyber-skirmish that ensued in the wake of Luka's announcement and launch.
Tako Luka shares pretty much the same voice as (or high pitched) Luka herself, regardless of voice bank.
The first Tako Luka video which got more than 100,000 view counts. Kagamine Rin and Len make attempts to speak English to Tako Luka, which fail as they cannot pronounce their words correctly. Hatsune Miku comes in and asks Megurine Luka what to eat. As Luka deliberates what to eat in Japanese, Rin and Len realize that this whole time Luka could actually speak Japanese.
Tako Luka is one of the Vocaloid derivatives that became officially recognized by Crypton Future Media, the publisher of the Character Vocal Series for VOCALOID2. The other derivatives bearing this distinction are Sakine Meiko, Akita Neru, Yowane Haku, and Hachune Miku.
Officially has been products such as phone charms and plush toys. She is also bundled with a Megurine Luka Nendoroid. If more than one version of Tako Luka is sold of any given item, a lottery is usually established for the item wherein one of 3 faces are able to be bought. However, the buyer will not be able to determine which of the 3 he or she receives. So far, this has been carried out with the Tako Luka plush doll and the charm.
In the rhythm game, Hatsune Miku -Project DIVA- (series), Tako Luka has made many a cameo and is available as an accessory. In the game's PVs she is usually spotted scampering around the scene or waving her tentacles at the viewer.
A Tako Luka puchi was also bundled with the Luka Megurine Nendoroid