The Japanese language is spoken by around 130 million people, and by many linguists is considered a language isolate; meaning that it is a language without roots to another language and largely developed on its own. Some will note resemblances with Korean (another considered language isolate) e.g. similar sentence structure and grammar, but neither are mutually intelligible and is still considered a separate language family.
Japanese uses 3 different writing systems. Hiragana, and Katakana each having about 46 different characters and Kanji having countless characters, though only about 1,500-2,000 are needed for fluency.
Little is known about the early developments of Japanese because up until the introduction of Chinese characters Kanji (漢字) there was no known writing system to write Japanese. Old Japanese used several different systems to transliterate Japanese using Chinese characters. One way was to just write in classical Chinese and then translate into Japanese, though helpful as it could be understood by those in areas with Chinese influence it was not without obvious difficulties in practicality and usability to the Japanese speaking masses. This system is still taught in high schools and universities as Kanbun (漢文) and is needed to understand important historical documents.
Regardless of what many people in the west may think, Japanese is not related to the Chinese languages; they merely adopted their writing system. Much like if English or Spanish adopted it instead.
Take the phrase “I ran to the bus stop, so I’m tired.”
If English were to adopt kanji like Japanese did, it would look something like this:
“私走-ed to the bus停, so 私am疲-ed.”
Another method that was used was Ateji (当て字), they chose a select few characters based on their sound rather than their meaning to write Japanese as it is spoken. It often ignored the existing meaning of characters, though some writers sometimes chose a particular character instead to write a sound specifically to add further meaning. While much more efficient as this system did not require knowledge of thousands of Chinese characters, it still took much time to write even a single word and was not intelligible by Chinese readers. Through reading with ateji, there was now a system to read Japanese as it was spoken; but the characters chosen, to a person literate in Chinese may be given a separate understanding of the text, be it positive or negative.
Ateji is not as commonly used today, it was also once often used to write foreign or borrowed words, much like katanaka is used now. There are still some remnants of this in modern Japanese 寿司 寿= “su” meaning Congratulations or longevity, and 司= “shi” meaning boss; so somehow “old boss” means sushi! Often times when non-Japanese people want their names written in Japanese (or Chinese for that matter) this is the system that will be used.
So before you go and get a tattoo of your name, be sure you check the meaning first. For example, the name Smith (In Japanese, su-mi-su); though it could use the characters酢魅簾(sumisu, or with a meaning like “blind vinegar monster”) maybe something more beautiful would be preferred, 守美子(sumisu, or “beautiful protected child”) or you can take the more common and safe bet by just sticking with the katakana (スミス) as they only represent sounds not meaning.
Since ateji took so long to write and with the issues of meanings behind the characters, meaningless simplified sound characters were developed to represent the sounds used in Japanese. These new characters are known as Hiragana and Katakana. They both represent the same sounds but different ways of writing, kind of like uppercase and lowercase letters. Originally Hiragana was a woman’s script known for its beautiful flowing characters, and Katakana was a man’s script, know for it sharp strokes; often used to write pronunciations of kanji. Now they are both used by everyone; with Hiragana being used for writing grammar, children’s books or written above a kanji character to show its reading, while katakana is used to write foreign borrowed words or to create emphasis.
The Kana’s beside their original character origin (an example of Ateji).
Kanji is a writing system originating in China but can also be used with writing Japanese, Korean and Vietnamese. Now Vietnamese almost never uses Chinese characters as they adopted a modified french alphabet, Korean rarely uses it, but is still taught from middle school as it is sometimes used in academic/medical writing to make meanings more clear; Japanese, while it does not use as many as Chinese, uses kanji daily in everyday life.
Unlike most writing systems where there are letters with a sound that you use to build a word. Chinese instead is written by essentially drawing pictures that represent things or ideas much like ancient Egyptian. Unlike the ancient Egyptian civilization, the Chinese civilization has continued on; occasionally modifying, simplifying and creating new characters as needed as new things and ideas were invented/introduced. What was once drawings of trees, animals, and mountains, over the centuries turned into the characters used today. As new characters were needed for new words and ideas often times preexisting characters would be added and built together to create an original character. So while there are thousands of different characters there are only a hundred or so “root/base characters” from which the rest are created by using them. So maybe even if you do now know how it is read, you may get an idea based on the root characters.
So, if you know that 石 = rock and 少 = little, you may be able to infer that 砂 =sand.
While this is not always the case, or it is not always so obvious, it can certainly help.
In Japanese, kanji is used to write things with concrete meanings; things like “I”, “she”, “car”, “water”, “anger”, “run” etc; but it is not so great at writing grammar like “to”, “and”, “so”, “~ing”, “~ed”, etc.
Like the above sample phrase “I ran to the bus stop, so I’m tired.”, In Japanese it is written: 私はバス停に走ったから、疲れました。
As you can see it uses all three writing styles; kanji for concrete things, hiragana for the grammar, and katakana for the foreign word “bus”.
Unlike in Chinese languages where, when you see a character it has one reading…
Take the character for sun/day:
明日 – (tomorrow)
Japanese Kanji can have many different readings, as they already had a functioning language when they adopted the Chinese writing system. They assigned characters based on how they were used in Chinese but by using preexisting Japanese words; when there was no preexisting word they would either adopt from the Chinese reading or make up one based on other used pronunciations.
Again, we use the character for sun/day 「日」but in Japanese it has many readings depending on the actual word.
onyomi: nichi (ni), jitsu
kunyomi: hi( bi, pi), ka, fu (u), su, iru (i), teru (te), tachi (ta)
(pronunciations in bold are more common)
今日 – kyou (today)
明日 – ashita (tomorrow)
日本 – nippon (japan)
木曜日 – mokuyoubi (thursday)
日曜日 – nichiyoubi (sunday)
本日 – honjitsu (this day, today)
生年月日 - seinengapi (date of birth)
毎日 – mainichi (everyday)
一昨日 – ototoi (day before yesterday)
明後日 – asatte (day after tomorrow)
While some readings are more common there are some others that are rare and historical remnants. Kanji will usually have an Onyomi (chinese reading) and Kunyomi (native Japanese reading) reading; sometimes multiple! The Japanese had a different way of thinking from the Chinese, and a completely different structure for language. Along with adopting characters during different time periods from different Chinese languages then evolving on its own for several centuries, we get the Japanese that we have today. So needless to say, the task of learning Kanji is difficult, it is not impossible.
Again we can relate this to English with our different words for/using sun related terms and how we borrow from Latin and Greek along with our original Germanic roots:
sun, sunny, sunday, suntan, solar, parasol, lunisolar, solar plexus, solaris, heliotheraphy, heliophobic, day, today, thursday, daydream, etc
Quite often foreigners studying Japanese will complain “Why don’t they just use hiragana? Kanji is too hard!”
Well, without kanji, texts will become even longer, and because the Japanese language only has a limited amount of sounds there are many homophones; if you have learned kanji, when you see a character you can automatically know what it means without any ambiguity. Kanji aids in speed reading, and it has a rich and artistic history. It has worked pretty well for so long; they are not going to change their entire language just so someone can read the new Naruto comic easier.