You Do Need power plug adapter while traveling from Syria to Japan.

Here is Why You Need An Adapter

The outlet and plug type used in Japan are A and B and in Syria are C, E and L. This is how they look like.

Syria

In Syria, outlets of type C, E and L are in use.

Type C

Type E

Type L

Japan

In Japan, outlets of type A and B are in use.

Type A

Type B