The unique sweetness comes from onions, carrots, and other additions like honey and grated apples.
Curry was introduced to Japan in the late 1800s by the British. Today, curry has become a staple of the Japanese home and is widely available in restaurants and food halls in departmental stores.
The popularity even extends beyond Japan, and you can find its presence in many other Asian countries. Japanese curry is quite different from most other curries of the world, it has a thicker consistency and the taste leans on the sweet and savory side.