The copula だ

Grammar: Assertion and Declaration

だ is the plain “is”. It links a noun or な-adjective to what it describes and asserts it as fact.

Usage Notes

だ conjugates: past だった, negative じゃない and ではない, conjectural だろう. Its polite counterpart is です.

Casual sentences drop だ freely, especially in questions (「元気(げんき)？」) and feminine speech (「きれいね」).

Before the explanatory の it becomes な, as covered on the 〜のだ page.

Formation

1. Noun ＋ だ
   • 彼(かれ)は高校生(こうこうせい)だ
   • "He's a high school student."
2. な-adjective ＋ だ
   • この町(まち)は静(しず)かだ
   • "This town is quiet."
3. 〜だった (past)
   • 昨日(きのう)は休(やす)みだった
   • "Yesterday was a day off."
4. 〜じゃない (negative)
   • 冗談(じょうだん)じゃない
   • "This is no joke."
5. Dropped だ (casual)
   • あれ、先生(せんせい)？
   • "Huh, is that the teacher?"
   • Note: Casual speech, questions, and feminine speech often omit だ entirely.
6. Noun ＋ な ＋ の (before explanatory の)
   • 猫(ねこ)なんだ
   • "It's a cat, you see."
   • Note: だ changes shape to な before the explanatory の／んだ.

Common Uses

Stating What Something Is

The plain assertion of identity or property.

Yui, Sacchan, and Kotoha go on an early-morning patrol to check for any issues in their neighborhood. Because it’s so early, none of the shops are open yet, and the streets are empty.

さっちゃん:

「朝(あさ)は平和(へいわ)だ」

“Morning is peaceful.”

結衣(ゆい):

「朝(あさ)は平和(へいわ)だね」

“Morning is peaceful, isn't it?”

琴葉(ことは):

「異常(いじょう)なし」

“No abnormalities.”

View Full Example

The Dramatic Standalone

A bare noun plus だ carries force.

だ Dropped

Casual and feminine speech leave the copula silent.

Takeo runs after a mother and her child to give them a shoe they dropped. Due to Takeo’s large size and loud steps, the mother and child get frightened and run from him. After he manages to return the dropped item, Takeo returns to his friends. Rinko remarks that the scene was like “A Bear in the Forest”. Sunakawa recalls the song.

砂川(すなかわ):

「あーイヤリング拾(ひろ)って追(お)いかけるやつね」

“Ah, the one who picked up an earring and chased after.”

猛男(たけお):

「そうか　熊(くま)だと思(おも)われたのか」

“I see. It's that I was thought of as a bear?”

View Full Example

Here, the だ after やつ is omitted.