Nintendo isn't including an AC Adapter with the Japanese version of the 3DS LL. But for those who don't have an AC Adapter from their current Nintendo portable, the cost to pick up a new one won't be too high: a mere ¥1,000.
That's the new price of the official 3DS AC Adapter starting July 12. The current price is ¥1,500.
3DS LL can use your current 3DS AC Adapter, or the AC adapter from your DSi or DSi LL.