Japanese Primer
Introduction
This material details one way to achieve basic Japanese fluency. Assuming you are starting with no skills in the Japanese language and are not familiar with kanji (example: 漢字), this curriculum will likely span several years with work to be done each day. I recommend you read the full curriculum before starting since some parts are to be done in parallel.
In this material, I assume your native language is English; however, this is not required--simply replace references to English as the native language with your native language.
Baseline
Before discussing our own methodology, let's consider the way native Japanese people learn Japanese on average. This will be our baseline. Typically, Japanese people start by consuming spoken Japanese for years from birth. Grossly generalizing, by around age 5, such people are fluent in spoken Japanese albeit with a limited vocabulary and are perhaps missing grammar constructs used in formal scenarios.
In addition to consuming, Japanese people also start speaking Japanese out of necessity. Conservatively measured, babies start speaking around 2 years old.
Assuming between the ages of 0 and 5 a baby is actively consuming spoken language for 8 hours a day, that totals to 14,600 hours of listening typically with accompanying visual and tactile feedback. Assuming a baby spends roughly 4 hours a day speaking between the ages of 3 and 5, that totals to roughly 3000 hours of speaking practice.
Naively assuming children are not exposed to reading until they enter school, we can say that Japanese people are conversationally fluent before they attempt reading and writing. The subset of kanji the government requires schools to teach is mastered over the course of 12 years in school, from elementary school through high school. Typically Japanese people master reading these kanji before the end of high school because they encounter them earlier in their environment--through entertainment, literature, written conversation, etc. So, 12 years is a conservative upper limit.
Summarizing this, Japanese people typically first spend years to achieve conversational fluency and then even more years to achieve literacy, with tens of thousands of hours of practice consuming and producing. While obvious, I ought to note that in this time Japanese people are not just learning language, especially babies who are also learning to conceptualize and abstract and who are developing social skills. However, throughout this entire time, Japanese is a necessity for social survival. The learning time scale and environment and the function of the language in Japanese peoples' lives are important points to keep in mind for us who are often students of--not dependants on--the language.
Applicability of the Baseline
The baseline above incorporates time spent in infancy and early school years. I assume readers here have already passed that time in their life. This presents a challenge. When just starting to learn Japanese, the easiest material to consume will be that made for children, and your ability to produce will be a very young child's at best for some time; however, our peers in our native language don't operate in this economy anymore. We don't have the benefit we used to of going to the schoolyard and growing together in our language skills via cross-polination of ideas and conversations centered around material made for children.
If you are learning, say, Spanish and you already know English, you can effectively read Spanish material from day 1. You can't necessarily understand anything, but should you need to type some word into a computer or try and match written text against someone speaking over it, you can do so rather effortlessly. For example, even without typing the accent marks, you can likely look a word up quickly. Therefore, you can practice listening comprehension, reading, and things such as making and using vocabulary flashcards in that language from day 1.
This will not be the case with Japanese. If you wanted to first become conversationally fluent before attempting literacy, you would likely still find vocabulary lists and flashcards useful to help reinforce the meaning of words you are exposed to in conversation or audio content. Yet, without knowing the Japanese writing scripts, you would not be able to read the flashcards. (You could write all content in English, but if you are tempted to do this, I would recommend at least using Japanese syllabaries instead.)
It is possible that people who become conversationally fluent before becoming literate first develop command of vocabulary based on conversational utility, so when such people learn how to read or write a particular word, they are simply learning the graphical representation of what they have been saying for quite some time.
In our case, although perhaps more challenging, for efficiency's sake, we will be honing our listening and reading skills simultaneously. This means that we will be ingesting brand new vocabulary into our curriculum most frequently by reading, meaning we will have to simultaneously learn to recognize the graphical representation of some word, learn its pronunciation, and learn its meaning.
Still, let the idealized baseline above motivate you--it is possible to attain conversational fluency and literacy in a matter of 2 or 3 years as opposed to 10+. With that said, let us consider our methodology.
Tools
Besides general Internet access, a pen, and paper, this curriculum relies on a spaced repetition tool. Familiarize yourself with the spaced repetition concept. One popular spaced repetition tool is Anki.
If you will consume written Japanese content online as part of your learning, I also recommend installing a browser plugin that allows you to conveniently translate Japanese to English by simply mousing-over or tapping words. One such plugin is yomitan.
Reading and Writing
Japanese has three scripts: hiragana, katakana, and kanji.
Together, hiragana and katakana are called "kana." Kana is a syllabary akin to the English alphabet. Kanji are Chinese characters, logograms, although the Japanese have also introduced additional characters unique to Japanese. You will need to learn all hiragana, all katakana, and a subset of the kanji to achieve basic literacy as written Japanese combines all three scripts. For example, here is a sentence in Japanese that says, "Alice studies Japanese," which uses elements of all three scripts: アリスは日本語を勉強する。
Learning the Kana
There are roughly 50 characters in modern hiragana and 50 characters in modern katakana. Additionally, there are two diacritical marks (゛ and ゜) which can be added after many characters to modify their sounds. Lastly, there are some special kana forms used to produce sounds common outside of Japanese but not native to Japanese itself, such as ディ for "dee," which is a combination of "de" and a small "i." I recommend you simply rote memorize the kana with your spaced repition tool.
For recognition, an entry in your tool could simply feature one kana character on the question side and the English pronunciation on the answer side. For example:
Question: ぺ
Answer: pe
If it helps you memorize the kana, consider also writing the character a few times each time you see it in your spaced repetition tool. Note that Japanese characters have a stroke order, an official way to move your pen when writing characters. If you will write the kana, I recommend you look up the stroke order and follow it, although you can of course still produce the kana without it.
If you want to practice production, simply reverse the entry in your spaced repetition tool, flipping the question and the answer. Also, when you see the English pronunciation, write the character before checking the answer.
To help retain what you learn, search for text written in kana in the wild and read through it. It does not matter if you don't understand what any of it means. At this point, you are simply trying to identify the kana and improve your reading speed.
Learning the Kanji
Toward basic literacy, we will learn the jouyou kanji. This is the subset of kanji considered by the Japanese government and Ministry of Education to constitute baseline literacy for people who have completed schooling in Japan through high school.
Unlike kana, kanji are often more complicated characters, and the jouyou set contains 2,136 characters at the time of this writing. Additionally, most kanji have more than one reading. We rote memorized the kana, but we will use some memory aids to help learn the kanji. Every kanji has a radical, an element used to organize the kanji in a formal list such as a dictionary. Every radical has a meaning. We will create mnemonics about each kanji by telling short stories incorporating the radical, and these mnemonics will help us remember the meaning of the character. We can also extend the mnemonic to help us memorize one or more readings of the kanji as well.
For example, the character 灯 means lamp. The main radical is 火, fire. In fact, the rest of 灯 are also radicals. 亅 means barb, and 一 means one. I could then say that a lamp in the old days was one bit of fire attached to a barb-like holder. One reading of the kanji is とう which sounds similar to the English "toe." You put the fire at the end of the barb-like pole to keep it away from you, so you don't burn your toes.
Alternatively, since 一 placed on top of 亅 to make 丁 means street, we could say the fire in the street are those old-style gas lamps that light your way so you don't stub your toe at night.
The story may be silly or far-fetched, but whatever helps you remember the meaning and perhaps one reading of the kanji is beneficial. The stories, and even the radicals, are crutches that are meant to fall away and even out of memory over time as the meaning and readings of kanji become second nature to you.
As noted earlier, most kanji have multiple readings. These readings are divided into on'yomi (Chinese readings), kun'yomi (Japanese readings), and nanori (Japanese readings used particularly in names). Instead of coming up with complicated mnemonics that encapsulate all readings, I find it easier to just memorize one reading and then learn the other readings in context while consuming Japanese in the wild.
I recommend dividing the jouyou kanji into groups based on the school grade in which the kanji are taught. This is grades 1-6 for about the first 50% of characters, and the remaining characters are taught throughout secondary school. After grouping the characters by grade, I recommend sorting them by frequency. This helps most for the large group taught throughout secondary school, which you might also want to further divide into smaller groups arbitrarily. When grouped this way, you could learn all kanji for grade 1 and then start consuming reading material for first-grade students. I recommend this approach to reinforce what you learn.
For recognition, an entry in your spaced repetition tool might look like
Question: 灯
Answer:
Meaning: lamp
Reading:
On'yomi: とう
Radical: 火
Mnemonic: a lamp is like one bit of fire carried on a barb-like pole
Similarly to kana, if you want to also practice writing the kanji, you could add a writing portion to your spaced repetition review strategy. Kanji also have a stroke order which I recommend following.
For production, similarly to kana, you can flip your spaced repetition entry.
Building Vocabulary
It will be easiest to build vocabulary after you can read the kana and the jouyou kanji.
One way to go about learning vocabulary is to find pre-made decks of common words for your spaced repetition tool. These decks have the benefit of being sorted by frequency in some popular medium (such as newspapers), so you are bound to encounter these words often when consuming "everyday" native material, and these words will also be useful to carry out general conversations. One challenge of such material is that there will inevitably be kanji you may not have learned yet if you have not worked through all of the jouyou kanji. Thus, you may end up doing additional work, learning both vocabulary and new kanji.
Another option to bootstrap your vocabulary is to study vocabulary sets made for the early levels of the Japanese Language Proficiency Test (JLPT). Level N5 will have elementary vocabulary, level N4 will have more advanced vocabulary, etc., through level N1. N5 and perhaps N4 should be sufficient to bootstrap your basic vocabulary enough to transition to consuming source material.
If you want to build vocabulary as you learn the kanji, you can consume source material targeted at school grades for which you've already learned the jouyou kanji. This will help you retain the kanji you've already learned, and I generally recommend this.
I recommend you learn vocabulary in or accompanied by sentences that use the vocabulary in context. This is more engaging and helps give a sense of how a particular word is used. If you are entering your own words into your spaced repetition tool, I recommend a technique called sentence mining. Sentence mining is simply consuming source material and making entries in your spaced repetition tool containing sentences you find that contain a word you want to learn. It is best if you generally understand the sentence with the exception of the word you want to learn, otherwise the sentence may contain too many unknown elements and distract from learning the target word.
A sentence card entry in your spaced repetition tool may look like the following, where "L1" is your native language and "L2" is your target language.
Question:
Vocab: 昼ごはん
L2: 昼ごはんはラーメンを食べた。
Answer:
Reading: ひるごはん
Meaning: Lunch
L1: I ate ramen for lunch.
Building Grammar
You will build grammar naturally over time as you consume source material.
To expedite learning common grammatical patterns, I find grammar resources tailored for the JLPT to be useful. These resources usually focus on everyday-Japanese grammatical patterns, and they often demonstrate the grammar in sentences which you can mine and add to your spaced repetition tool. The sentences often use kanji and vocabulary targeting the resource's corresponding JLPT level, meaning that you can learn from these resources while you work through the jouyou kanji, and they will even help reinforce the kanji and vocabulary you are learning and your reading ability.
N5, N4, and N3 grammar are generally helpful to build daily conversational ability whereas N2 and N1 delve more into formal Japanese.
Grammar dictionaries are useful to learn the meanings of many grammar points you will encounter in the wild, and these dictionaries often have a wealth of sentences to mine and acquire vocabulary from. However, these dictionaries usually do not sort grammar points by how frequently they are used in everyday Japanese, and many times grammar entries do not indicate whether the grammar points are used in casual conversation or only in formal circumstances or even only in writing. Because of this, dictionary-like grammar resources are best used for reference only.
A grammar entry in your spaced repetition tool might look like the following.
Question:
Grammar: 〜たことがある
L2: ラーメンを食べたことがありますか。
Answer:
Meaning: to have done something before
L1: Have you eaten ramen before?
Building Listening Comprehension
Listening comprehension is built in two ways: passive listening and active listening.
Passive listening is what happens when you play Japanese audio in the background while you do something else. You're not focusing intently on just the audio and trying to understand what is being said, but you are exposing your brain to how Japanese sounds. This helps build your Japanese "head voice"--your ability to voice Japanese words in your head as a native speaker would pronounce them. It also helps with general pronunciation of syllables and how their sounds change in some words.
For example, if your native language is English and you have only read (not heard) Japanese, you may pronounce です as "deh-soo." If you've ever heard this word spoken by a native, you will know it is commonly voiced more as "des." Similarly, you may be familiar with the sport called Sumo. In English, I voice this as "sue-mow," with both syllables taking the same amount of time to say, and I stress the first syllable. In Japanese, this word is voiced more like "smo" with the pacing (not intonation) being similar to "smo" in "smoke," and the second syllable is stressed more.
You can technically perform passive listening almost anytime--when doing chores, exercising, cooking, or even when studying something else in Japanese--by just playing something Japanese in the background.
Active listening has the benefits of passive listening, but you are also giving your undivided attention to listening, trying to understand precisely (or roughly, depending on the complexity of the material) what is being said.
Regarding material for building listening comprehension, I recommend language-dense material such as podcasts, interviews, the news, movies, anime, etc. I generally don't recommend content such as songs since the manner of speaking is more artistic than you would otherwise hear or use in everyday Japanese, and I also don't recommend language-terse material since there is a lot of time spent not listening to Japanese. If you use subtitles for visual media, I recommend you use Japanese subtitles. Otherwise, you may accidentally turn the listening exercise into more of a native-language-reading one. Even then, I recommend eventually turning off the subtitles and trying to comprehend using listening alone--there are no subtitles when speaking with people in the wild, at least not at this time.