Planning began in early 2007, and was devised immediately after Yamaha announced their VOCALOID2 engine, and a bilingual vocal which was originally going to be called "Hatsune Miku". The reason for a bilingual Japanese and English vocal was to break the restrictions set by katakana-English, which was noted for its tendency to sound off. Luka's provider was selected from a list of several candidates. Due to reasons, the voicebank was delayed and the plans for "Hatsune Miku" changed, becoming a different Vocaloid entirely.
Her introduction was firstly by code (CV03) and her existence was made known during the Kagamine original release promotions. She was intended to be the last of the CV series vocals. The earliest reference to Luka's release was the existence of "CV03", which was listed on the Character Vocal Series webpage on August 10, 2007. Originally CV02 (the Kagamine release) was set to be released at the end of 2007 with their final vocal CV03 (Luka's release) set to be released soon after after. 
The first recording of Luka's voice was in December 2007. According to later reports, originally while they were waiting for the recording process to start, both Yu and a woman from marketing began to sing "Happy Birthday" in the style of Marilyn Monroe to John F. Kennedy. This made the five men in the recording booth break out in laughter. When they stopped laughing, Wataru Sasaki announced it was time to begin recording the English vocal. One of the words she was asked to record, being confirmed as "nerd" in various deliveries. According to Yu, due to the fact she needed to record in a single tone, she could not go out drinking the day before as it would make her voice bad.
The voice of Luka was recorded in 4 hours sessions and took 5 days.
Recording was resumed the following year in April, 2008. A further five sessions occurred, amounting 15/16 hours. The recording of the Japanese was noted to be constant, whereas with the English, the singer always sounded "angry" and everything took 4-5 times as much work, and English samples were cut at a length of more than 0.5 seconds. The experience with producing the Kagamine Rin & Len act2, helped resolve many issues with the English vocal.
On the 5th of January, 2008 the first letter of her surname was revealed with the promise of more information to come. On the 6th of January, Megurine Luka was revealed. Crypton advertised Luka's vocal database as "Japanese," like Kagamine Rin and Len's.
However, a second voicebank was shown shortly before her release that gave her the capability to sing in English. This was revealed on the 14th of November 2008.
At the time of Luka's release there was a growing interest in English speaking VOCALOIDs. Luka offered both languages for the price of one, giving Japanese VOCALOID users the chance to test their skills with English capable VOCALOIDs. Her English voicebank was produced in a series of experimental recordings. Her vocal provider Yū was not used to the recording process, which ended up taking eight months.
Crypton Future Media chose Megurine Luka's name to express its hope that she would transcend borders and cultural barriers. Her surname literally means "sound that goes around." Luka was designed by the Japanese illustrator Kei, who had previously created the designs for Hatsune Miku and Kagamine Rin and Len.
By default, her software will be set on its Japanese vocal and Producers will have to manually select her English one.
Important: It became a popular myth among some groups of fans that Luka's Japanese vocal was more adept at commanding the English language than her actual English vocal. This, however, has often been proven incorrect as the Japanese vocal lacks much of the needed samples for producing suitable English. See English - Japanese for more details.
Both vocals were sold together at the same price as past Character Vocal Series vocals, making her cheaper to purchase than buying a VOCALOID solely built for English separately. Like previous vocals in the series, Luka is not designed to be a realistic sounding singer as she is designed to be a Character Voice vocal. Her vocal direction was "moody and serious".
Demo .VSQ files for "UP" were made available for download from the Crypton Future Media blog as part of the promotion for her release.
Vocal traits as noted:
This is the first example of a multibank release that had voicebanks for more then 1 language, being English and Japanese. This proved to be useful for many fans who wanted to try experimenting with English VOCALOIDs.
Mastering both languages gives the user a much greater advantage in terms of language capabilities over using either voicebank alone.
The bilingual Megurine Luka product was ranked as the most advanced VOCALOID software released during the VOCALOID2 era. This is because it requires multilingual knowledge in addition to music knowledge to make full use of the vocal.
At an optimum known vocal range of #D5, both Megurine Luka and SONiKA joint hold the title of second highest VOCALOID2 vocal.
This particular product does not sound very close to the Yū Asakawa's own voice, to the point where even she noted that this version didn't sound much like her at all.
RIP=RELEASE, however, is a known example of when the package did sound like her.
She is capable of competing with some of the highest vocals in VOCALOID2 overall.
Unlike Hatsune Miku, Luka's voice provider is more experienced, producing more accurately pitched samples than her predecessor. This makes Luka an overall better singer than Miku with less editing/effort. Thus she was considered as the best singer for the Character Vocal Series with the best singing abilities.
Luka was more capable of producing a multiple of tones than past Character Vocal series vocals and alternating GEN factor will open up a range of roles for Luka. While she can offer less unique sounding tones compared to Hatsune Miku and does not always easily morph to sound very different, she offers many more stable tones and is less prone to sounding robotic.
Luka's vocal does not collapse on fast passages, this is owed to her strong bass.
At the time of Luka's release, she was considered the easiest vocal to repair tonal faults of, though this title was lost by 2011 to other VOCALOIDs such as the Append vocals, Nekomura Iroha and VY1.
Software issues as noted:
According to information at the of her V3 development, Luka suffered from sounding tight-throated on higher pitches. She much more prone to tone collapse on higher notes as a result.
Altering the GEN factor higher than GEN 96, makes Luka head towards the collapse of her vocal. At GEN 100, her treble will fail completely, making decreases of volume at this point more difficult.
Despite including English within her package, Crypton Future Media did not offer technical support during the VOCALOID2 era for that particular voicebank library, but did offer help for the Japanese voicebank library.
The inclusion of English and Japanese left Luka as the VOCALOID2 vocal most likely to encounter issues with either of the two VOCALOID2 engine versions. This is because the English and Japanese vocaloids did not always share the same version of the engine and users had to track what VOCALOIDs had which version of the software.
Luka's total file size was 3GB, though it was not the most demanding of the vocal libraries for VOCALOID2, it was the most resource demanding of the Japanese releases VOCALOIDs at the time.
Being the first case of a bilingual voicebank to exist within VOCALOID, it came with a number of "first time" issues. The first is the notable weakness of one language over the other, in this case the English was considered much weaker then the Japanese. This issue has become a notable concern among multilingual VOCALOIDs ever since.
Despite both voicebanks having the same range and tempo, there is a slight tone difference between the two voicebanks with English being notable to be "softer". This too was the first example to present this and would become a notable issue with all future multilinguals. The explaination for the difference in the two voicebanks is that English itself is a blending language, therefore it appears "softer" for this reason alone.
Both voicebanks have a issue with quietness and can mumble at times.
This was the best overall Voicebank produced by Crypton Future Media at the time of the release in 2009 in terms of quality due to its smoothness and high quality samples. This was a stark contrast to the Kagamine release before it.
Megurine Luka remained one of the best vocals in Japanese VOCALOID2 and was only beaten by Nekomura Iroha, both the Appends and the VY series in terms of overall quality.
Phonetic notes as noted:
Her vocal has a habit of collapsing during pronunciation of "サ" ("sa") related lines.
Genre: Latin, Jazz, Ethno Pop, House, Dance, Electronica Optimum Range: D3 ~ D5 Optimum Tempo: 65 ~ 145 BPM Total Tempo (min-max): 80 BPM No. of Keys: W ~ 15, B ~ 10, Total ~ 25
Package details as noted:
ENGLISH vocal was intended for English and had the same vocal direction as the Japanese vocal also included within the package. She is capable of 2,200 word connections from the English dictionary.
Her English dictionary is more limited than other English capable VOCALOID 2 voicebanks at 2,200, this is the least amount of words known by a released VOCALOID. A Extra dictionary which increased the amount of words Luka could form, was later supplied.
Vocal traits as noted:
She is the only other English capable female voicebank in the VOCALOID 2 range besides Prima to have breaths included in her voicebanks.
The recommended optimum ranges for the English voicebank are also identical to that of the Japanese voicebank, meaning in theory they will both will work for similar types of music.
The English vocals pronunciations are softer and less clear than the Japanese vocal.
She has all the core sounds needed for basic English and as other English vocals can recreate English better then her Japanese vocal can for this reason.
The Dark L from her English voicebank has a syllabic behavior, allowing using on its own and extend its duration.
She does not have the capabilities to roll the "R" sound and is the only VOCALOID 2 English capable VOCALOID besides Sweet ANN to not have it.
It has been reported that she does not seem to have many distinct vowel related diaphones in her sample library in her English voicebank, making her voice less smooth than other English capable VOCALOIDs within the VOCALOID2 era. Some diaphones are missing altogether.
When discussing Megpoid English, NeutrinoP noted that Luka has bad sounds among her good sounds. This leads to having a lack of adjustment room because of the lack of good sounds to begin with.
Software issues as noted:
While the Japanese vocal was one of the best Japanese voicebanks on sale in VOCALOID2, the same could not be said for the English vocal due to its mixed issues.
Due to these issues, it can compete with Sonika over which is the overall worst English voicebank of VOCALOID2.
Luka's English has a reputation for having too much softness and sounding bored. It is something her developers are much aware of.
An old trick within the Western VOCALOID fandom is to have Luka's VOCALOID2 English voicebank and SONiKA sing together. If correctly done both voices will blend together. The advantage of this is that both VOCALOIDs effectively hide each others' flaws since both VOCALOIDs have similar vocal ranges. In this case, Luka's higher quality samples can help hide Sonika's flawed ones.
As she was only marketed in Japan, very few producers could make use of this voicebank and it was far less used then the Japanese one due to the unfamiliar English Phonetics. It was also quite difficult for English speakers to purchase her for a time in addition, so very few English speakers could also get hold of her to use her.