N3DS/N3DSXL Capture will be released by Katsukity on March. Or at least that what it says on her Website.
Google Translation:
http://3dscapture.jp/blog-entry-667.html?sp
EDIT
You can Preorder them now
http://www.3dsvideocapture.com
Google Translation:
Is Katie. New3DSLL Monster Hunter packs and Majora of I mask pack arrived. Special pack of past 3DSLL is often the structure of the body foundation is different were obtained for verification. Please follow-up and the other for a while waiting. China and South Korea factory test version enters the holiday for Chinese New Year will be the stock since March.
http://3dscapture.jp/blog-entry-667.html?sp
EDIT
You can Preorder them now
Welcome to the Game Direct Shop!
Special discount code JJKS3AKV8NQ1
We've started accepting pre-orders for the following capture kits:
New 3DS XL (USA)
(No New 3DS (USA) is planned)
New 3DS (EU), New 3DS XL (EU)
New 3DS (JP), New 3DS XL (JP)
We are planning to ship the capture kits somewhere between the middle of March and early April, 2015.
We will ship them in order that we received.
As it is difficult to assemble the kits, we will ship 10 capture kits a day at the beginning.
Since the new 3DS will be thinly distributed for the first 6 months, the price of the game console itself is at a premium.
The price for new capture kits will be reviewed every 3 months.
http://www.3dsvideocapture.com