Toyota Yaris Owner's Manual page 47

CAUTION
Make sure the both buckles are cor-
rectly located and securely latched.
Failure to properly match the buckle
and tab may cause serious injury in
case of an accident or a collision.
40
PS13522
To release the hooked end tab, insert the
key into the hole on buckle 1 and allow
the belt to retract.
PS13523
CAUTION
Do not use the rear center seat belt
with either buckle released. Fastening
only the shoulder belt or lap belt may
cause serious personal injury in case
of sudden braking or a collision.