You Do Need power plug adapter while traveling from Hong Kong to Niger.

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, E and F and in Hong Kong is G. This is how they look like.

Hong Kong

In Hong Kong, outlets of type G are in use.

Type G

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F