What Is the Difference Between は and が? New and Known Information in Japanese (Level 3)

Introduction

In Level 2, you learned the basic difference between は (wa) and が (ga).

あわせて読みたい

What Is the Difference Between は and が? Japanese は and が for Beginners (Level 2) In Level 2, learn the difference between は and が by focusing on what is already shared and how to identify who someone is. A beginner-friendly guide for N5–N4 learners.

That was necessary. But many learners still feel unsure, even after learning the rules.

At Level 3, the focus changes.

Here, は and が are not about grammar labels. They are about information flow.

In this article, you will see how Japanese uses が to introduce new information, and は to continue talking about what is already known — using the opening of the famous folktale Momotarō as an example.

Ha and Ga Difference: Level-by-Level Overview

Key Idea (Level 3)

At Level 3, the most important question is:

Is this information new, or already known?

Japanese speakers constantly make this choice, often without thinking about grammar rules at all.

To see this clearly, let’s look at a very familiar story.

Example from Momotarō: Why が Comes First

The opening of the famous Japanese folktale Momotarō begins like this:

「むかしむかし、あるところに、おじいさんとおばあさんが住んでいました。」

At this point in the story:

• The old man and the old woman are introduced for the first time
• The listener has no prior information about them

That is why が is used.

At Level 3, this use of が is best understood as:

が marks first appearance and new information.

It tells the listener: “Here is something you don’t know yet.”

Using は here would sound unnatural, because there is no shared context yet.

Switching to は: Continuing with Known Information

The story continues:

「おじいさんは山へしばかりに、おばあさんは川へせんたくに行きました。」

Now the situation has changed.

• The old man and the old woman have already been introduced
• They are part of the shared story context

Because they are now known information, Japanese switches to は.

Here, は does not mean “topic” in an abstract sense.It means:

“You already know who this is. Now I will tell you more about them.”

This shift from が → は is one of the most common and natural patterns in Japanese.

How は and が Change in Real Conversations

The same が → は pattern appears not only in stories, but also in real conversations.

At Level 3, understanding this pattern helps you follow explanations, introductions, and descriptions more naturally.

Let’s look at some common conversation examples.

Conversation Example 1: Introducing Someone New

A: だれか来ましたか。
Did someone come?

B: はい、男の人が来ました。
Yes, a man came.

Here, 男の人 is new information. The listener does not know who this person is yet.

That is why が is used.

Conversation Example 2: Continuing with Known Information

A: その男の人は、今どこですか。
Where is the man now?

B: その男の人は外で待っています。
The man is waiting outside.

Now the man is already known to both speakers.

Using は signals that the conversation is continuing with the same person.

Conversation Example 3: Explaining Details After Introducing a Group

A: わたしには兄が二人います。
I have two older brothers.

Why が?

Because “two older brothers” is new information.
The listener is learning about their existence for the first time.

Now look at what comes next.

B: 一人目は東京に住んでいます。
The first one lives in Tokyo.

二人目は大阪に住んでいます。
The second one lives in Osaka.

Why は?

Because the brothers have already been introduced as a group.
At this point, the speaker is no longer introducing new people.

Instead, they are explaining and comparing known members within that group.

At Level 3, this is an important pattern:

• Introduce a group with が
• Explain or divide it with は

Level 3 Summary: Why は and が Change

At Level 3, the difference between は and が is not about grammar labels like “topic” or “subject.”

It is about information flow.

Japanese uses が to introduce something new into the conversation, and は to continue talking about what the listener already knows.
This logic applies across stories, explanations, and real conversations.

That is why the same noun can appear with both が and は.

• First mention → が
• Continued explanation → は

The grammar does not change.
Only the information status does.

Understanding this makes many natural Japanese sentences easier to follow, especially in narratives and everyday speech.

What’s Next? (Level 4)

Before moving on to more abstract or stylistic uses, it is important to understand this stage first.

👉 What Is the Difference Between は and が? Contrast and Emphasis in Japanese (Level 4)

あわせて読みたい

What Is the Difference Between は and が? Contrast and Emphasis in Japanese (Level 4) At Level 4 (N2), は and が are no longer just about new or known information. Learn how they express contrast, generalization, limitation, and emphasis—and what speakers really mean behind the sentence.

Mastering Level 4 will make the higher-level uses of は and が feel much more natural.