Konnichiwa! As I explained before, there are 4 types of characters/letters used in Japanese.
Only one of them (Romaji) can be entered on a normal keyboard
(or an English-language 2DS's touchscreen keyboard, for that matter).
However, there is a way around this (although it doesn't seem to work here).

You see, there are these "secret codes" you can enter into a search, that will be converted into Japanese (or Chinese, and probably other languages, too) letters.

Now, you're probably wondering:
"Why would I want to do that if I can just type it with English letters?".
Well, aside from just wanting to learn a new language, it also allows you to search for Japanese websites. If you're really into Anime or Manga (like me), it's pretty nice to be able to do that.

Anyway, here's how. First, you need to know how to spell the name/word in Japanese. Depending on what you're looking for, this can be really easy, or really hard.

For simplicity's sake, let's say you want to look up a Pokémon in Japanese. The easiest way to get the Japanese name of anything in Pokémon (including the Japanese names of Trainers, Items, Places, Moves, Abilities, etc.) is to look it up on Bulbapedia. Usually, the Japanese name is at the top of the page, written in both Romaji and Kana (generic term for all Japanese letters), right next to the English name.

Once you know that, it's just a matter of knowing (and properly entering) the codes.
The best way to learn the codes is to use an English to Japanese translation website (I use Eudict.com).

In the next lesson, I will teach you how to do this. Sayonara!

http://www.google.com/search?client=ds&hl=en&rls=com.nintendo.ds:2+US&oe=utf8&ie=UTF-8&q=%E3%83%9D%E3%82%B1%E3%83%A2%E3%83%B3
(This should search for the word "Pokémon", in Japanese.)