Mitsubishi 2010 RVR Owner's Manual page 51

Seat and restraint systems
2. After making sure that the seat belt is not twisted, insert
the small latch plate (B) into the detachable anchor (C)
aligning the marks (D) on the plate and buckle until a
"click" is heard.
2
2-24
To detach
1. Insert the latch plate (E) of the center seat belt into the slit
(G) on the detachable anchor (C) and release the center
seat belt from the detachable anchor.