The second Japanese script is Katakana, a syllabary that functions almost identically to Hiragana. There are 46 basic characters used in modern writing, as well as 2 archaic characters ヰ(wi) and ヱ (we) for a total of 48 characters.
Diacritical Marks – ゛and ゜
Just like with Hiragana, Katakana makes use of the dakuten and handakuten markers and the resulting sound changes are identical.
Yōon
Yōon also works the same way as in Hiragana. You take the -i row consonant sound you want and pair it with a small ヤ、ユ、or ヨ for the vowel that you want. All the resulting sounds are identical.
Chōon
This is where things get slightly different from Hiragana. Long vowels in Katakana are expressed by the use of the character ー which is called a Chōonpu. It is written horizontally in horizontal writing and vertically in vertical writing.
アー
イー
ウー
エー
オー
Sokuon
The double consonant / glottal stop works the same way as in Hiragana. Simply insert a small ツ where you want the pause.
サッカー / Sakkaa / Soccer
バッグ / Baggu / Bag
リッジ / Rijji / Ridge
Extended Usage
Since one of the main uses of Katakana is to transcribe foreign words, the number of possible sounds you can create with it has been heavily extended to accommodate sounds in other languages that do not exist in Japanese.
The following sounds are not exactly “standard” but are in increasing use, especially on the internet. Here are just a few of the new creations that exist.
Kuwashii Japanese 