You first see this guy in front of the lava spill, talking to the MATORAN who holds the key to the Lightstone Mine. After you’ve cleard the path to the Mine, he can be seen getting instructions from the Foreman. There are quite a few similar looking MATORANS scattered through out ONU-KORO, and even one just outside the tunnel to PO-WAHI, but all of the rest of them have pieces that are very obviously dark-grey instead of black.

To build this MATORAN, you need to swap ONEPU’s feet with those of a NUHVOK VA or HAFU from the CD-pack, and give him ONUA’s black PAKARI.