In modern Japanese, Chinese characters (Kanji), are used to express native Japanese as well as words from Chinese origins. Those Chinese characters can be found in Chinese languages, Korean and also Vietnamese (before the 20th century). But looking more closely to those characters we can see that many characters have two different forms even though they are exactly the same (known as Traditional and Simplified Characters in Chinese languages). In Japanese this duality is called Shinjitai (新字体/ New form characters) and Kyûjitai (舊字體/ Old form characters). Kyûjitai refers to the form of Kanji that were in use prior to 1946, especially of those that were later simplified. Shinjitai refers specifically to the simplified forms of certain characters as part of language reforms following World War II.
At the beginning of the 20th century, scholars in Japan and China started to think about simplifying the Chinese characters which were hard to write and in order to increase the rate of literacy. Those scholars proposed a very easy idea which was to replace difficult characters by simplified versions which were already used when writing informal letters or known as grass script. So for example the character 學 (GAKU/to study) was simplified to 学 which was already used in informal writing. Shinjitai were not "created" as they were always used during centuries, but rather they were given official status. Thus following the simplification of Kanji, the character 學 was considered as obsolete. China began this simplification following the Chinese nationalist government's policy (Guomingtang) in the late 1920's. On the other hand Japan "officially" simplified the characters following their defeat in World War II after the United States of America put pressure on the Japanese government to simplify the characters. The few countries that did not simply the Chinese characters were Taiwan, Korea and to a lesser extent Vietnam. The fact of simplifying characters is still a very important debate in China (Mainland and Taiwan) and is considered a cultural and identity issue.
Kyûjitai, literally "old character forms", are the traditional forms of Chinese characters used in Japanese. The old forms are still in used in Taiwan and Korea and are only known as 漢字 meaning "Chinese characters" in those countries. After World War II, simplified character forms were made official in both Japan and China. However, in Japan fewer and less drastic simplifications were made. For example the traditional character (Kyûjitai) for "wide" is 廣. As just said before unlike China, attention was paid in Japan to the aesthetic balance of the characters in their new form. Thus the Japanese simplified character (Shinjitai) of 廣 became 広 while the Chinese simplified character became 广. This was a great criticism towards China because many people considered that the simplified Chinese characters were oversimplified and lost their original meaning by removing too many aesthetic and semantic elements of the characters. Kyūjitai continue in use to the present day because when the Japanese government adopted the simplified forms, it did not ban the traditional forms. Thus traditional forms are used when an author wishes to use traditional forms and the publisher agrees.
Shinjitai, literally "new character forms", are the forms of Kanji used in Japan since 1946. Some of the new forms found in Shinjitai are also found in Chinese (Mainland China), but Shinjitai are generally not as extensive in the scope of their modification. Some of the simplified characters arose centuries ago and were in everyday use in both China and Japan, but they were considered inelegant, even uncouth. Shinjitai were formed by reducing the number of strokes in Kyûjitai. This simplification was achieved through a process (similar to that of simplified Chinese) of either replacing the left part which is the semantic element (點 became 点) or the right part of the character which is the phonetic element (號 became 号). Some exceptions were made and the entire character was replaced by another one and not by removing some part of the character (體 became 体) . Nowadays Shinjitai became the norm when writing in Japanese.
Kyûjitai VS Shinjitai
Although Shinjitai are easier to write, people generally think that Kyûjitai are more "pure" and more beautiful as the number of strokes and the semantic elements were not removed. The following characters are the most common Kanji that were simplified in Japanese (Kyûjitai・Shinjitai) :
會・会 (KAI/to meet)
賣・売 (BAI/to sell)
與・与 (YO/to give)
來・来 (RAI/to come)
覺・覚 (KAKU/to remember)
讀・読 (DOKU/to read)
Which set should I learn ?
In Modern Japanese Kyûjitai are not used anymore. You can only find them in ancient books, shrines or in people's last name. So learning Kyûjitai is only a bonus but it is a very good bonus to know them if you want to learn deeply Japanese as they are the original characters and also because they are still used in countries like Taiwan, Hong Kong and Korea. Also Japanese people will be very impressed if you show them that you can write some Kyûjitai especially when doing calligraphy because only few people can write Kyûjitai in Japan. Last but not least, as the difference between Kyûjitai and Shinjitai is very minimal compared to the difference between Traditional and Simplified Chinese characters, it is not very hard to learn some Kyûjitai if you already know Kanji and they will help you to understand even better Japanese language and culture.
More informations about Chinese characters (Kanji) in our article here!