Singaporean Adeline Leng expected to start studying at a language school in Japan last April but is still not able to travel to the country due to its strict COVID-19 border controls.

Leng, 26, began the process of applying 16 months ago and since then it has been one long, increasingly fraught wait.

"When the timeline passed and we got to about August, after the (Tokyo) Olympics, and September, October, that is when the stress of not being able to enter Japan started to get to me," Leng said in an online interview.