You Do Need power plug adapter while traveling from Liechtenstein 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 Liechtenstein are C and J. This is how they look like.

Liechtenstein

In Liechtenstein, outlets of type C and J are in use.

Type C

Type J

Niger

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

Type C

Type D

Type E

Type F