Translation guide
Expresses that two or more actions, events, or states occur at the same time. Japanese uses various patterns depending on whether the subjects are the same, the actions are ongoing, or the timing is precise.
To say that two actions or events happen at the same time, often with the same subject.
Attach to the stem of a verb to mean 'while doing'. Both actions are performed by the same subject. The main action is the second verb.
音楽を聴きながら勉強する。
I study while listening to music.
Adverb meaning 'at the same time' or 'simultaneously'. Can be used with different subjects.
二人は同時に話し始めた。
The two started speaking simultaneously.
Pattern meaning 'at the same time as ~'. Used with nouns or verbs in dictionary form.
彼が入ると同時に会議が始まった。
The meeting started simultaneously as he entered.
Means 'together with' or 'as'. Indicates that one change or action happens along with another. Slightly formal.
年を取るとともに、体力が落ちる。
As you age, your physical strength declines simultaneously.
To describe doing one action in the middle of another ongoing action, often with the same subject.
Means 'while ~ is happening'. The second action occurs during the first. The subject can be the same or different.
子供が寝ている間に、本を読んだ。
I read a book while the child was sleeping.
Similar to ながら but more formal and often used in writing. Attaches to verb stem.
彼は歩きつつ考えた。
He thought while walking.
To emphasize that two events occur at precisely the same instant.
Means 'the moment ~ happened'. Emphasizes immediate simultaneity.
ドアを開けた瞬間に、電話が鳴った。
The moment I opened the door, the phone rang.
Literary expression meaning 'as soon as'. Indicates that the second action happens almost simultaneously with the first.
彼は家に着くや否や、雨が降り出した。
As soon as he arrived home, it started raining.
To describe multiple people doing something at the same time.
Adverb meaning 'all at once' or 'in unison'. Used when a group acts simultaneously.
生徒たちは一斉に立ち上がった。
The students stood up simultaneously.
ながら is used when the same person does two actions at once, and the first action is the background activity. 間に is used when an action takes place during a time period, and the subjects can be different.
テレビを見ながら食事する。
I eat while watching TV. (same person)
私が料理している間に、彼は掃除した。
While I was cooking, he cleaned. (different people)
While 同時に is a direct translation, it can sound stiff in casual conversation. Use ながら or 〜ている間に for natural speech.