You Do Need power plug adapter while traveling from Tonga to Yemen.

Here is Why You Need An Adapter

The outlet and plug type used in Yemen are A, D and G and in Tonga is I. This is how they look like.

Tonga

In Tonga, outlets of type I are in use.

Type I

Yemen

In Yemen, outlets of type A, D and G are in use.

Type A

Type D

Type G