My Janitor Dad Is the Mecha God

Three years after he failed to protect his wife, once-legendary mech pilot Vic Thorne has sunk into a humbling existence as a janitor. When his estranged son Leo is almost killed by a spoiled heir during a televised mech trial, Vic finally uses the neural key his late wife left him. That act awakens Type-Zero, humanity's lost war machine, just as an Abyssal invasion threatens to wipe out the world.