For the Hiragana, the examples with their specific functions are as below:
Syllabary:
ひ = Hi、represent one syllable for each letter
Description:
にこっGRIN = smile (微笑み)
Name:
はやて = Hayate
For the Katakana, the examples with their specific functions are as below:
Onomatopoeia:
ピピピピピ Pipipipipi = the sound a crock make (目さまし時計の電子音)
カチャン KATCHA = the sound a porcelain make (陶器同士がぶっちあった時の音)
コソコソ WHISPER WHISPER = the sound of undertone, an action (声を潜めて話す様子)
Foreign loan words:
コンピューター / パソコン = computer / ＰＣ（計算機）
Emphasizing:
ボール = ball, even though it is normally post as ‘球’, we may use Katakana for emphasize the word
Terminology:
サイコロジー = psychology (心理学)
For the Kanji, the examples with their specific functions are as below:
Ancient Onomatopoeia:
卑弥呼 = Himiko, the Queen of Yamatai Kingdom (姫子)
[Source: ≪魏志倭人伝≫]
Terminology:
経済 = economy
Name:
明治天皇 = Emperor Meiji
For the Romaji, it is used for vocal, especially for foreigners:
For the Kaomoji, it is used to impress Word Arts, commonly used for emotional reflection on face or actions, by composing American Standard Code for Information and Interchange (some Japanese web-users had been arguing that it is JIS code) in specific order:
(-_-#) / (▼皿▼メ) = angry / furious (怒る)
(￣○￣) (￣◇￣) (￣o￣) (￣ー￣) = good night, imitate the lips (おやすみ)
[Source: http://www.kaomoji.com/kao/text/ikaru.htm]
Description - Idiom, contains both Kanji and Hiragana:
愛の鞭 = rigours education
頭に来る = something make me mad
