The model of the Fort-type monsters you'll be meeting later on in the game, this monster is an step-up from the Ikaruga Mk.I in both attack and defense, although its HP isn't much higher. Its attacks are Burn Missile, which deals Fire-elemental damage to a single target; Alarm, which allows it to summon Balthazaars; Dual Chamber Gun, which deals physical and Fire-elemental damage to a single target; and finally, Call Lightning, which hits all Vanguards for Thunder-elemental damage and causes Paralysis.
Most of its skills aren't an actual threat, but given that Call Lightning can cause large damage to all your party and Paralyze them, you'll want to keep Misha singing Thunder Guardian in order to reduce the damage you'll receive from it, as the Guardian will use that skill very frequently. As for the Balthazaars it will summon with Alarm, don't pay any attention to them, and just focus in bringing down the Guardian. If you ever get a break from the constant Call Lightning attacks and want to attack using Song Magic, keep on mind that the Guardian has high resistance against all elements except for Thunder, so you'll be better using Songs like Energy Ball to damage it.