It comes from the Sanskrit words "Yaksha" meaning a guardian-spirit of hidden nature, and Raja, meaning "king".
There are 2 variants of Yaksha Raja:
The clawed one acts as a leader: It focuses heavily on melee attacks and has higher HP.
The mainly gunned one acts as support: It focuses on pot shots and has lower HP.
It should be noted that, unlike Ravana, its shots do not pass through material (i.e they are not High Piercing). Use this to your advantage by hiding behind Aragami when you see the charging shots.
In GE2 and GE2RB, it is a regular Aragami along with other Yakshas in both Story and Free missions.
While based on God Eaters as well, God Arc Soldiers are manmade, cybernetic organisms mass-produced for annihilating Aragami; Yaksha Raja are creatures that either spawned from fallen God Eaters, or came into being from Oracle Cells that possessed the bodies of God Eaters and/or ordinary humans alike.
Yaksha have the ability to slowly track players.
In a cutscene that covers Nana's backstory, Yaksha Raja's were found gathering on the area where Nana is located along with her dead mother due to her Power of Blood.
爆散宝珠 (Explosion Ball)
Fires an energy ball at the enemy. Affected by gravity.
光柱召珠 (Ray Caller)
Fires a homing bullet that summons a satellite beam.
鬼神封珠 (Sealing Bead)
Fires a delayed homing energy ball. Can inflict Seal.
Note: Both variants of Yaksha Raja have the same Aragami Bullets.