Japanese language has one of the most complex writing systems in the world; not only does it use thousands of Chinese characters, but it's also the only language where four different scripts can appear together in the same sentence. In this series, I'm going to explain the difference between these scripts, why and how they should be used, and the best way and order in which to learn them.
Rōmaji (ローマ字), commonly known as latin alphabet outside of Japan, is never used by native Japanese speakers to write full sentences, yet it's widely used all over Japanese media. The Latin script has a modern, in vibe to it which is why many new Japanese companies prefer it to kanji for use in logotypes and advertisement, fashionable magazines use it in headlines, and Japanese TV shows overflow with silly English exclamations. In addition to that, newspapers don't mind using English abbreviations, youth uses it for interjections in online conversations, and most street signs in major Japanese cities display transliterated names and instructions under their Japanese counterparts. Many teachers and textbooks use romaji to teach beginners Japanese, and many even think that romaji should completely replace traditional scripts. However, frequent readers of this blog know that I am highly against the use of romaji outside of scientific publications and advertisement, and this seems to be the right moment to explain my position.
While it comes to teaching Japanese, I am of the opinion that hiragana AND katakana should both be thought as soon as possible, ideally in the first week or two of the learning process. While it may be tempting to stay with romaji for as long as possible, learning kana is in fact crucial and helps one to avoid many difficulties in the future, including, but not limited to bad pronounciation, incorrect understanding of verb conjugation & particles, and insufficient knowledge of kanji in the more advanced stages of the learning process which leads to lack of accessible reading material and subsequently a major progress slowdown.
To answer the second group of people, romaji can never replace kanji and kana in day-to-day use of the Japanese language. While many point out the more or less successful transition of countries such as Vietnam (formerly using Chữ Nôm and classical Chinese) or Philippines (Tagalog used to be written in Baybayin), the situation is completely different in case of Japan. While this may seem strange to a beginner learner of Japanese, any native speaker will agree that for several reasons, Japanese is hardly readable and undestandable while written in pure kana or romaji.
Firstly, Japanese has a very low number of syllables and contains a record number of homophones. While this creates opportunities for puns so popular among Japanese, and allows artists to create great creative works (reminiscent of the Chinese poem Lion-Eating Poet in the Stone Den consisting of 92 characters, all with the sound shi), it also has its negatives; a sentence written in hiragana may have several ambiguous meanings even when read in context.
Secondly, even in western languages, good readers recognize entire word shapes, not the individual syllables or even letters which would be slow and inefficient. Words written in kanji are usually shorter and have better distinguishable shapes which promotes this type of learning. Also, while Chinese characters are used, one can quickly spot different words and particles which is impossible when using a romaji. In western languages, the problem is solved by adding spaces between words, but this solution is far from perfect as it makes the text less compact and creates many new typographical problems (e.g., rivers of white).
haha ha ha de hashi wo hashi no hashi ni haru ni haru.
My mother with her teeth chopsticks on the edge of the bridge in spring will stick.
This spring, my mother, with her teeth, will stick chopsticks on the edge of the bridge.
Of course, this example is extreme, but some parts of it, like はははは, appear quite regularly and, while understandable, are hardly readable when written in hiragana or romaji. On the other hand, when one writes the same sentence with kanji, it may still sound funny, but it is not ambiguous or difficult to read.
Thirdly, there is no single standard Japanese transliteration guideline and each of the many systems has it's own advantages and weaknesses. Creating a single ruleset would be very difficult, if not impossible, as the needs of different groups of users are completely different.
Last, but not least, deprecation of kanji could potentially reinforce class divides as the richer part of the population would afford to study kanji outside of official educational institutions and thus differentiate themselves even further from the lower classes.
However, despite all the negatives, romaji has one more very important function. Unless you have a Japanese keyboard and use the kana input method you'll have to use a Japanese IME which will transcribe romaji into kana & kanji on the fly.