If you want to learn Japanese as efficiently as possible, you will want to start inputting Japanese “in the wild” as soon as possible. Inputting is the only path to fluency, and the sooner you can start inputting, the better.
But what and how much do you need to know before you actually pick up your first manga and begin struggling through sentences? To understand what you need to know, you must first understand why you need to know it.
Building a foundation in Japanese is important because, unlike for machines, inputting is painful for us humans. Inputting by its very nature requires struggling to understand each sentence you read or listen to, which is the source of pain. And the less you know, the more painful, and therefore unsustainable, your ability to input Japanese will be.
For instance, if you know nothing about Japanese, it will be extremely painful to try and understand even this simple sentence: 「私の猫の名前はタマです。」 (My cat’s name is Tama). If you started at 0, you would need to look up each character of ひらがな (hiragana), カタカナ (katkana), and 漢字 (kanji), figure out which parts of the sentences are words and which are particles, and finally, if you made it that far, read up on the relevant grammar. All of that effort would be necessary just to decipher that my cat’s name is Tama. And you would need to repeat this effort over and over and over again for every sentence you input.
The amount of effort required to input Japanese when you know nothing is obviously a huge ordeal and not realistically sustainable.
This is why your Japanese language study should begin first with foundation building before input. By building a foundation, you will lower the pain it takes to input Japanese to a healthy level. This kind of pain is akin to the pain you get after exercise: it lets you know you worked out and is feedback that you are growing.
While making inputting less painful is the goal of foundation building, it’s important to recognize that inputting will still be painful when you first start out, no matter how much you prepare. It’s easy to think learning 6,000 vocab words (a multi-year journey I don’t recommend) will make inputting painless. But that is wishful thinking. More importantly, preparing too much risks other dangers to your language journey just as big (or bigger) than pain: boredom and the eventual disappointment and discouragement you experience when you realize inputting is hard despite your extensive preparations.
So don’t focus on building a foundation with the goal of making your eventual input of Japanese painless—that is a fantasy. Your goal with foundation building should be to learn just enough so you can handle inputting manga and no more.
Here are the essentials you will need to create a foundation that enables you to start inputting full time:
Mastery of ひらがな and カタカナ. You’re not going to be reading any Japanese in the wild written in romaji. If you are reading Japanese with romaji now, it’s time to give up that crutch and move to ひらがな and カタカナ.
—Resources: Start by going through Tae Kim’s section The Writing System. Once you can write all ひらがな and カタカナ characters from memory, you will have sufficient mastery.
Steady Study of Core 漢字. You won’t need to know any 漢字 to get started inputting Japanese that has 振り仮名 (furigana), which are smaller kana printed either above or next to 漢字 to indicate their pronunciation. But as the 漢字 in the preceding sentences shows, most Japanese will not have these helpful characters to help you out. You will eventually need to start distinguishing and remembering individual 漢字 to read most material in Japanese written for native Japanese speakers. Studying 漢字 can also speed up your entire learning process.
—Resources: I’m biased here, but I recommend using Ashiba for studying 漢字. Most other programs like WaniKani or RTK will teach you keywords that are not particularly useful to remember. Ashiba is paced so you can maintain a rate of 10 new 漢字 each day and will teach you up to 2,150 漢字. Ashiba is designed so you learn useful keywords for each 漢字 and are exposed to common (i.e., useful) words that use each 漢字.
Knowledge of the 2,000 Most Common Words in 日本語. Studying vocabulary has many benefits, and bootstrapping a core vocabulary is most effectively done through flashcards. Why 2,000? It’s the minimum amount of knowledge required to make inputting bearable. If you try inputting native 日本語 while knowing fewer than 2,000 words, you’ll find yourself constantly looking up words in a 辞書 (jisho) to the point where inputting even interesting content will be too painful to sustain. You need to have some footholds to cling onto when starting. But going significantly beyond 2,000 is counterproductive because you will be delaying the start of inputting, which is when the real learning begins.
—Resources: Ashiba foundational vocab decks are coming soon! While Ashiba vocab decks are not yet complete, Anki, a free flashcard app, is the best alternative. You can find a decent Anki deck with 2,000 core vocab flashcards here.
Core Grammar. Being familiar with the fundamentals of how words are put together to convey meaning is essential to inputting. Navigating long sentences will be laborious and difficult if you are frequently looking up the grammar to understand each sentence you input. In addition, conversational Japanese often abbreviates words that signal grammar. It’s hard to both learn the rule and the deviation at the same time (e.g., ものだ and もん), so having a grasp of the fundamentals will make learning such deviations easier.
—Resources: While there is no consensus on what makes up “core” grammar, having command of grammar constructs in the section “Basic Grammar,” “Essential Grammar,” and “Special Expressions” on Tae Kim’s website will suffice. I also recommend familiarizing yourself with the grammar points in the “Advanced Topics” section so they don’t surprise you when you first see them.