一方（で）while; on the other hand
You set a second fact beside the first. It may pull the other way, be about someone else, or simply be another thing the same person does.
on the other hand
This job has a steady income, but the hours are irregular.
and also
My older sister works during the day and also goes to school at night.
How to form it
Plain form + 一方（で）
The で can be left out. A な-adjective keeps な: 豊かな一方で. A noun takes である, and in news writing also の: 期待の一方で, "alongside the hopes". 一方、, 一方で、 or その一方で opens a new sentence.
- Before it
- One side: a fact, a quality, or something someone does.
- After it
- The other side, often with も.
- Where you'll meet it
- News, reports, essays, presentations and careful conversation. News stories turn to the other side with 一方、.
What the two sides can be
This town is rich in nature, but it has little public transport.
Two sides of one thing. 反面 would fit too.
The older sister chose to study abroad, while the younger brother decided to take a job in their hometown.
Two different people. のに対して would fit too.
He teaches at a university and also runs science classes for local children.
One person doing both. Neither of the other two can say this.
In casual conversation, people join the two things one person does with the て-form or し, and も: 昼間は働いているし、夜は学校にも行っている.
Opening a new sentence
The population is growing in the cities. In the countryside, meanwhile, it keeps falling.
The new library has more seats. On the other hand, the gaps between the shelves are narrower than before.
Close neighbours
反面N3
Two sides of one thing, usually good against bad.
This medicine works well, but it also has strong side effects.
に対してN3
Two different things side by side: A is like this, B is like that.
My older brother is quiet, whereas my younger brother talks a lot.
ながらN5
"While" for two things you do at once. 一方で is not about time.
I do my homework while listening to music.
一方だN2
At the end of a sentence it is a different expression: something keeps going one way, and there is no second side.
The work keeps piling up.
Check yourself
1Which one fits?
母は
Choose an answer to see why.
2"I ate dinner while watching TV."
Choose an answer to see why.
More detail
Both sides can be labeled, as in English "on the one hand…, on the other…":
On the one hand, empty houses are increasing in the countryside; on the other, the housing shortage in the cities goes on.
More sentences
This material is light, but it doesn't stand up well to heat.
The company is expanding its overseas business while cutting the number of its stores at home.
She is a researcher, and she is also involved in supporting young entrepreneurs.
The new contract is cheap, but the areas where you can use it are limited.