Translation guide
Expresses simultaneity, contrast, or concession. Japanese uses different structures depending on whether actions occur together, or a contrasting point is added.
Two actions happening at the same time.
Attach to the ます-stem of a verb to mean 'while doing'. The subject must be the same for both actions.
音楽を聴きながら勉強する。
I study while listening to music.
Used when one action occurs during the duration of another. The subjects can be different.
私が料理をしている間に、彼はテーブルを片付けた。
While I was cooking, he cleared the table.
Adverb meaning 'simultaneously'. Can be used with verbs or nouns.
Formal pattern meaning 'at the same time as'. Often used in written language.
彼が到着すると同時に会議が始まった。
The meeting started at the same time as he arrived.
Introducing a contrasting or opposing point, similar to 'on the other hand' or 'nevertheless'.
Used to present a contrasting fact or situation. Common in both spoken and written Japanese.
彼は優しい。一方で、厳しいところもある。
He is kind. At the same time, he can be strict.
ながら is used when the same person does two actions at once. ている間に is used when one action happens during the time another action is ongoing, and the subjects can differ.
歩きながら電話する。
I talk on the phone while walking.
私が歩いている間に、彼は走って行った。
While I was walking, he ran off.
二人は同時に話し始めた。
The two started speaking at the same time.
Literally 'the other side', used to show a contrasting aspect, often with a negative nuance.
便利な反面、使いすぎに注意が必要だ。
It's convenient, but at the same time you need to be careful not to overuse it.
Emphasizes the contrast more strongly than 一方で alone.
経済は成長している。その一方で、貧富の差は広がっている。
The economy is growing. At the same time, the gap between rich and poor is widening.
Can also be used for contrast, similar to 'at the same time' in English, but less common than 一方で.
この計画は魅力的だ。しかし同時にリスクも大きい。
This plan is attractive. At the same time, the risks are big.