You receive this companion on Coruscant.

She is melee DPS. She uses light armor and a single saber or a double-sided saber.

Her customization options are

Kira Carsen
Appearance 1 - Tanned Brunette Kira. (Balmorra)
Appearance 2 - Black Kira, hair in a bun. (Balmorra)
Appearance 3 - Asian Kira (Balmorra)
Appearance 4 - Blonde Kira, probably the most attractive of the Kira's. (Balmorra)
Appearance 5 - Emo Mohawk Punk Kira. (Carrick Station, Collector's Edition area)
Appearance 6 - Non evil, red headed Kira. (Balmorra)
Appearance 7 - Black Kira, with double pony tail action. (Carrick Station, Collector's Edition area)
Appearance 8 - Evil Kira. (Carrick Station, Collector's Edition area)

Kira is a fantastic companion for a Guardian. You are able to tank and she beats them down. T7 tends to pull to much agro for a tank speced knight.

And then there is the romance option. T7 just isnt smexy enough ;-)

You get the customization packs on several planets, usually in cantinas. The first one is on Taris, in the back of the cantina. The other one is on Balmorra, near the entrance.

However, there are 9 customization packs, and you can buy only the first 6 (from which there is only one that looks ok, the last one, which makes Kira a nice green eyed redhead). Those other three are either drops from flashpoints or as questrewards.

For the Jedi Knight mission "The Defector", flirting with Kira Carsen during the Ship Intercom conversations following the events at the Abandoned Mining Base will prevent players from being able to receive further companion conversations from Kira Carsen.

Workaround: Avoid flirting with Kira Carsen during "The Defector" mission. Players who have already flirted with Kira will need to wait for a patch before they will be able to have conversations with Kira but will still be properly accumulating affection with her in the meantime.

source: http://www.swtor.com/community/showthread.php?t=5533
Amber Green | Live Community Coordinator

Kira Customization 8 (Evil Kira) - also available on Ilum from the Security Key Vendor (Captain Kneely) right in the space station, for 12,500 credits. Doesn't go through any mob zones, so you can go pick this up immediately when you get your ship if you want (and have a security key).

Another thing - if you don't like her unending supply of floor-length dresses and can't find light armor pants (there don't seem to be many options that aren't dresses/robe bottoms), hit Social II and you can go to Balmorra and pick up some Social pants for her. Just run into the building from the landing spot, you can avoid the mobs (guards will be attacking them).

I'll will upload some screenshots of Kira Custom 6 and Kira Custom 8.

{In response to cyvaris' post} For those who need a visual ♥

Kira Carsen Customization 1
Kira Carsen Customization 2
Kira Carsen Customization 3
Kira Carsen Customization 4
Kira Carsen Customization 5
Kira Carsen Customization 6
Kira Carsen Customization 7
Kira Carsen Customization 8
Infected Kira Carsen Customization

@ demonolithic

I've heard that items on the CE vendor change, so maybe the Kira customization are sold at the CE vendor on the fleet, but just weren't for sale when you checked.

@cyvaris - the info you've posted on the locations of the customization kits is incorrect.

1-4, 6 can be found on Taris in the major port cantina.

We made a nice spread sheet to calculate the affection gain for all the gifts with each level, lol its a work in progress.

https://docs.google.com/spreadsheet/ccc?key=0ApqMWEUUXHsadG51N1VVRHY2ckVLdzVtLUhlUXVtLXc

Possibly true for all companions, starting from 0, you're better off buying rank 1 gifts at first. In fact you'll probably get best value by matching gift rank to affection rank.

With both technology and luxury, rank 1 gifts gave me 54 affection, while rank 2 gifts only gave 59, in the 0-2000 affection range.
After 2000 affection, rank 1 technology and luxury gifts dropped to 27 affection, while rank 2 dropped to 54.

Presumably the trend continues that way.

I am 27 and have 2036 affection with Kira and can say for certain that neither the CE vendor, the VIP Vendor or the Security Vendor sells a Kira Modification.... It appears that things must have changed during live. I did find 1-6 on Balmorra from GUUNTA.. So if there are any on Taris, then it would seem they moved them all off, which kind of sucks for those of us who spent 150$ for CE thinking there would be at least 1 there..

EDIT: Both Taris and Balmorra have Version 1,2, 3, 4, and 6, didn't realize 5 was missing.... sooo no idea where 5,7,8,9 are...

A quick fix for her lightsaber staying lit after she's holstered it... On my character.. her lightsaber stays lit while holstered if I exit my hoverbike, a conversation.. etc (often)

If I switch her from once of her stances to the other (or turn her current stance off then back on again), she'll turn off her lightsaber before holstering it... its annoying.. I know.. but bioware is slow to fix problems and this might help someone else out there... you have to expand her skill bar to see the stances... you can assign hotkeys to them to speed up the chore.

Hope this helps someone

We're working on spreadsheet to calculate affection gain by companion gifts :)

https://docs.google.com/spreadsheet/ccc?key=0ApqMWEUUXHsadG51N1VVRHY2ckVLdzVtLUhlUXVtLXc

....:::: Crew Mission Bonus :::::....
+ 10 Investigation Effeciency / +2 Bioanalysis Crit

No one post this yet & half the websites say +10 research... so hope this helps a few other people who are wanting to know.

Spoiler Alert:

She was born in the Empire, her parents are both Siths. She was being trained by the Emperor as part of the Empire Children program. She escaped and was cought by a Jedi Master stealing parts and was taken as a padawan without knowing her past.