You Do Need power plug adapter while traveling from Brunei to Equatorial Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea are C and E and in Brunei is G. This is how they look like.

Brunei

In Brunei, outlets of type G are in use.

Type G

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E