Mitsubishi i-MiEV 2011 Owner's Manual page 105

Seat and restraint systems
3. Pull the seat belt out slowly while holding the latch plate.
Push the latch plate into the buckle until you hear a
"click". Pull up on the belt to be sure the latch plate is
locked securely in the buckle.
2
NOTE
If the seat belt locks up and cannot be pulled out, pull it
once with force and let it retract all the way.
Then, pull the belt out slowly once again.
2-16
4. The lap part of the belt must always be worn low and snug
across the hips. Pull up on the shoulder portion of the belt
to take up any slack in the lap belt.