You learned all those polite ます・です sentence patterns, then watched a Japanese drama and couldn't understand a single line. That's because Japanese people don't use those forms in daily conversation. Casual speech uses the plain form, and on top of that, three rules make sentences even shorter.
Rule 1: か Is Replaced by Rising Intonation
Polite questions end with か:
食べますか？ → Do you want to eat?
In casual speech? Change ます back to the dictionary form (plain form), drop か entirely, and just raise your intonation:
食べる↑？ → Wanna eat?
That's all there is to it. Just raise your voice at the end, and the listener knows you're asking a question.
| Polite | Casual |
|---|---|
| ジュースを飲みますか？ | ジュース飲む↑？ |
| 部屋にテレビがありますか？ | 部屋にテレビある↑？ |
| 昨日の試験はどうでしたか？ | 昨日の試験どうだった↑？ |
There's also another substitute — the sentence-ending の (with rising intonation), which also indicates a question. It's especially popular with women:
どうしたの↑？ → What's wrong?
行かないの↑？ → You're not going?
デパートで何買ったの↑？ → What did you buy at the department store?
Rule 2: は, が, and を Can Be Dropped
Casual speech aims to be as short as possible. Three particles can be omitted in spoken Japanese:
- は (topic)
- が (subject)
- を (object)
See how much shorter things get:
| Full version | Casual (particles dropped) |
|---|---|
| 私は行きます。 | 私、行く。 |
| テレビがありますか？ | テレビある？ |
| ジュースを飲みますか？ | ジュース飲む？ |
| 僕は田中ですよ。 | 僕、田中だよ。 |
Important: Only these three particles can be dropped. に, で, へ, と and other particles must stay.
Rule 3: だ Vanishes Before か
The plain form copula だ (the casual version of です) has a natural enemy — か. Whenever だ is followed by か, だ gets "eaten":
そうですか。 → I see. (polite)
そうだか→ ❌ You can't say thisそうか。 → I see. (casual)
More examples:
| です → だ + か → だ gets eaten | Result |
|---|---|
| 暇ですか？ → 暇だ+か | 暇？ (both だ and か gone) |
| 本当ですか？ → 本当だ+か | 本当か？ or 本当？ |
| そうですか。 → そうだ+か | そうか。 |
But if there's no か after だ, then だ appears normally:
暇だよ。 → I'm free. (だ is alive and well)
本当だ！ → It's true!
All Three Rules in Action
Here's a complete casual conversation showing all three rules working together:
Polite version (textbook style):
A: もしもし、鈴木君、僕は田中ですよ。
A: 鈴木君、明日の夜は暇ですか？
B: うん、暇ですよ。
A: じゃ、カラOKに行きませんか？
B: いいね。行きますよ。
Casual version (real life):
A: もしもし、鈴木君、僕、田中だよ。(は dropped, です→だ)
A: 鈴木君、明日の夜、暇↑？(は dropped, ですか→だか→だ eaten→rising intonation)
B: うん、暇だよ。(No か, so だ stays)
A: じゃ、カラOKに行かない↑？(ませんか→ない + rising intonation)
B: いいね。行くよ。(行きます→行く)
Bonus: Two Intonations of そうか
そうか means different things depending on intonation:
- そうか↓ (falling) → I see. Oh, right. (understanding)
- そうか↑ (rising) → Is that so? Really? (questioning)
You can even drop the か:
- そう↓ → Right. I see.
- そう↑ → Really?
Summary
- Rule 1: Casual questions don't use か — use rising intonation instead, or use の for questions
- Rule 2: The particles は, が, を can be dropped in casual speech
- Rule 3: だ vanishes when followed by か
- All three rules often apply simultaneously, which is why Japanese people speak so briefly
- As a beginner, use ます・です when talking to Japanese people, but understanding casual speech is essential
Practice Questions
1. Convert this polite sentence to casual: 明日は何を買いますか？
Show answer
明日何買う↑？ or 明日何買うの↑？
Explanation: は dropped, を dropped, 買います→買う, か→rising intonation or の.
2. Convert this casual sentence back to polite: 「昨日のテスト、どうだった？」
Show answer
昨日のテストはどうでしたか？
Explanation: は was dropped and needs to be restored, だった→でした, rising intonation→か.
3. What do 「暇だよ」and「暇？」mean respectively? Why does one have だ and the other doesn't?
Show answer
- 暇だよ → I'm free. (declarative sentence, だ appears normally)
- 暇？ → Are you free? (question, だ got eaten by the implied か, then か became rising intonation)
Because of Rule 3: だ vanishes before か. The question implies か, so だ disappears.