You Do Need power plug adapter while traveling from Nauru to Nepal.

Here is Why You Need An Adapter

The outlet and plug type used in Nepal are C, D and M and in Nauru is I. This is how they look like.

Nauru

In Nauru, outlets of type I are in use.

Type I

Nepal

In Nepal, outlets of type C, D and M are in use.

Type C

Type D

Type M