Let’s get this out of the way: if you are new to Japan, and if you don’t already speak a second language other than your mother tongue, you likely have some misconceptions about learning a language. As an adult learning a foreign tongue, I can guarantee that you WILL NOT learn the language without this first tip:
I hate to be the bearer of bad news, but as an adult learning a new language, you must study. If you do not, you may eventually understand what people are saying to you, and you may be able to express yourself (albeit, very brokenly and not very well), but you will never actually become proficient in the language. STUDY. In particular, the Japanese language is radically different from other languages. In fact, the United States Military rates the Japanese Language as the most difficult foreign language to master for native English speakers. The grammar is different (there is often no subject, the verb comes at the end of a sentence, there are no gendered nouns, there is (an almost) separate honorific language within Japanese, etc.) and the writing system is complicated even for Japanese people. Even Japanese people have to study a lot to learn their own language so that it will be the same for you.
Focus on grammar, listening, vocabulary, and speaking.
Japanese grammar is radically different from the grammatical rules of other languages, so a firm understanding of Japanese grammar is essential.
When learning any foreign language, the ability to understand what is being said to you is crucial. When I first came to Japan, I used to leave my TV on in the background, and when sleeping, just to inundate myself with spoken Japanese. This was back in the pre-smartphone dark ages, but now, there are plenty of apps for studying Japanese (and indeed, any language) you can get on your phone. When you’re jogging or riding the train (something you will do a lot in Japan), listen to some Japanese.
Vocabulary is absolutely vital in learning a foreign language. The good news is that, according to many linguists, in order to attain “conversational proficiency” in a foreign language, a vocabulary of about 1,500 words is sufficient. You can gain this level in several months. Make a list of two or three hundred verbs, commonly-used nouns, adjectives, and adverbs, and every day, while drinking coffee in the morning, review these. Also, when learning new vocabulary, new words should be remembered with example sentences, because example sentences show how these words are used, especially for Japanese prepositions (joshi). For example, in Japanese, verbs usually have a transitive form and an intransitive form (for those who don’t remember elementary school lessons, transitive verbs take a direct object and intransitive verbs do not (for example, “I grow corn” (subject verb object) is the transitive form of “grow,” while “corn grows quickly” (subject-verb adverb) is the intransitive form)). In Japanese, many verbs take a clear transitive/intransitive form. Deliver, for example, can be “todokeru” or “todoku,” with “todokeru” being the transitive form and “todoku” being the intransitive form. By remembering these verbs with example sentences, you will be able to remember that the transitive “todokeru” takes the form “I delivered …..” and “todoku” takes the form of “…was delivered.” Trust me, remembering vocabulary with example sentences is the best way to remember them AND the correct way to use them.
As for speaking, this is where you practice what you have studied concerning grammar and vocabulary. This is crucial. One of the reasons Japanese people have difficulty when speaking English is that they study English for years, BUT THEY NEVER ACTUALLY USE IT. You may think, “I’ll be in Japan, so I will have an infinite number of opportunities to speak Japanese,” but the reality is that you likely will not. You will probably come to Japan with limited Japanese language skills, so naturally, you will find yourself surrounded by Japanese people who can speak English. You will likely then pass a year without really speaking Japanese. Nowadays, especially in Tokyo and other big cities, you can get by without speaking Japanese at all. YOU MUST FIND OPPORTUNITIES to actually speak the language with native Japanese speakers. I did it by going to local izakayas (pubs) and chewing the fat with locals. Another great way of finding speaking opportunities is by pursuing your own interests or hobbies. Go to a karate dojo, take up shodo (calligraphy), ikebana (Japanese flower arrangement), or the like. This will also help you make friends.
Don’t get ahead of yourself (minohodo shirazu)! Learning to speak Japanese and learning to read and write it are two different matters. Learning to read Japanese to the level of being able to read a book or a newspaper even takes Japanese people a long time. First, the Japanese language has three writing systems used simultaneously. Two of the writing systems (hiragana and katakana) are phonetic writing systems that are used, respectively, to indicate the inflectional endings of verbs and adjectives and foreign loan words and onomatopoeia, and these two can be learned in a few weeks. Learn them, inside and out. Also, learn the correct writing order for these characters, because this will help you when you tackle the third writing system, which is much more difficult. This third system, called kanji (Chinese characters), is complicated. There are thousands of these characters, and their “readings” (way to pronounce them) differ widely. If you learn the correct way to write the simpler hiragana and katakana, when you make your vocabulary lists, you can write these words in the kanji (which is how they will typically appear), and you can naturally learn the correct way to read these Chinese characters as you review your vocabulary lists. Learning to read Japanese requires a certain level of kanji knowledge, a certain level of grammatical knowledge, and a specific vocabulary level, so as explained above, you must first get your vocabulary and grammar in order. Writing comes even later. Nowadays, you will be text-messaging (line in Japan) your friends so that you will get some practice here, but without a strong grammar and reading background, writing will be difficult.
The Japanese Language Proficiency Test (JLPT) is the most widely recognized proficiency test for non-native speakers of Japanese. Currently, it has five levels, with the fifth level being the easiest and the first being the most difficult. When employers seek foreigners with Japanese language abilities, this is the test that is often used as the standard. As a general rule, for any job requiring Japanese language abilities, level two is the absolute minimum. The best thing about this test, though, is that it gives you a very structured approach to learning the language. For low-beginners, levels four and five will impart the most basic kanji and grammar. For beginners approaching the intermediate level, level three will impart kanji and grammar allowing you to have a conversational level. For the intermediate student approaching an advanced level, level two is great. And for the semi-advanced student who is approaching a level of fluency, level one will provide you with the required knowledge. More than that, having a test date gives you great external motivation to study.
The Japanese language is not impossible to learn. As long as you approach it with the understanding that it must be studied, and as long as you make the necessary efforts, you will learn. It is not impossible. Ganbare!