Toyota Lexusc Owner's Handbook Manual page 265

OCCUPANT RESTRAINT SYSTEMS
3. Fix the child restraint system with the seat belt.
4. Latch the hook onto the anchor bracket and tighten the
top strap.
For instructions to install the child restraint system, see "Child
restraint system" on page 226.
246
CAUTION
Make sure the top strap is securely latched, and check
that the child restraint system is securely by pushing
and pulling it in different directions. Follow all the
installation instructions provided by its manufacturer.