Basic unvoiced hiragana
These are the 46 basic hiragana syllables. Move your mouse over them to see their romaji equivalent. Starting top left and reading down the table, you'll notice that the pattern seems pretty regular: five basic vowel sounds (a, i, u, e, o) on their own, and then with a series of consonants in front of them (ka, ki, ku, ke, ko; sa, shi, su, se, so, etc).

Then, finally, there's n (which, if you were to pronounce it on its own, sounds like not "enn" but "uhnh" - think non-commital grunt, like you're a guy watching the FA Cup or the Superbowl and you think your girlfriend might just have said something to you from the kitchen). It's the one sitting in the top-right of the table below, and it's the only "closed" syllable in Japanese. It's only ever used in the middle of a word or at the end of a word, such as in shinkansen (bullet train). That's right, six syallables: shi-n-ka-n-se-n.

There are a few irregularities, though. Notice that where you might expect a si, we get a shi instead. The Japanese syllable in question just happens to sound more like a shi than a si, so that's how it's normally romanized. The same is true for ti, tu and hu, which are actually pronounced (and hence romanized) more like chi, tsu and fu. And the character which looks like it should be pronounced wo is actually pronounced o.

You'll also notice that there seem to be some gaps. There's nothing where you'd expect yi or ye to be, and they seem to have missed out wi, wu and we altogether. The sounds just don't really exist in Japanese, so don't worry about it unduly.

If you have a lot of spare time, on the other hand, you might like to make up your own pictograms and submit them to the Japanese Ministry of Education.