Very nice IDN.tv. Perfect name for the extension. 66M search results for 'ライブ'. 'live chat' has the highest Ovt. You have many options if you choose to develop a site.
I also count 4 .tv sites on the first page of Google.co.jp search results. Nice.
How do you reg hiragana and katakana? Can you reg hangul (korean)?
You can register most foreign scripts (including japanese and korean) at Idotz.net, dd24.net, or domainsite.com.
Idotz.net has a three character limit (which doesn't really make sense in Korean) but dd24 and domainsite do not have this limitation. Although Idotz is probably the cheapest.