Who are `comfort women`, why were they forced into into sexual slavery?

Comfort women were women and girls who were forced into sexual slavery by Japanese Army during and after the second World War.  

Most of these women were abducted from their homes in countries like Korea, China, Philippines,  Burma, Thailand, Vietnam and Malaysia (all of them occupied by Japanese Army). They were kept in Japanese Army's military stations located in these countries as sex slaves. 

In some case these women were also lured with job offers in factories and restaurants.  

Need for comfort women stations: 

Several military correspondence of Japanese Army tell that the idea behind 'comfort women'  was to prevent Japanese soldiers from committing rape crime in countries of their deputation and prevent the spread of Sexually transmitted diseases (STDs) among soldiers. 

First comfort station was established in Shanghai in 1932. Earlier comfort women were mostly Japanese prostitutes, who volunteered for the services. But as the Japanese Army expanded its operations to other countries, the need for more comfort women was felt. 

Why is comfort women issue now in news: 

On Monday, South Korea and Japan reached a landmark agreement to resolve the issue. The issue has long plagued ties between the neighbours.

The Japanese government feels "deep responsibility" over the comfort women issue and will contribute to a fund to help the women, Foreign Minister Fumio Kishida told a news conference after a meeting with South Korea`s Yun Byung-se.

"Prime Minister Abe, as the prime minister of Japan, once again expresses his feeling of heartfelt apology and remorse to all those who, as `comfort women`, experienced much suffering and incurred incurable psychological and physical wounds," Kishida said.

Yun said South Korea will consider the matter resolved "finally and irreversibly" if the steps pledged by Japan are fully carried out.