Fuuraimaru coming to GouJyuJin's rescue reminds me of an old ninja-based cartoon series, Ninja Senshi Tobikage.
Tobikage(which means flying shadow) is the smallest, but the most powerful of the ninja robots of the good guys of the series.
For the most part of the series, whenever the bigger three robots were in danger or on the verge of defeat by the villains, Tobikage appears out of nowhere, and destroy most of the enemies and turns the tide to the good guys' favor.
The situation would be much more similar if it had been Gokai-Oh in the fight instead of GouJyuJin. Because the other thing that Tobikage did was combining with the bigger robots to form beast mode mechas where were far more powerful than the humanoid mode, and destroy the rest of the enemy troops.
Preview
It is shown in the preview for the next episode that Fuuraimaru can combine with Gokai-Oh. So if it had been Gokai-Oh there was fighting giant Sundahl Jr., and Fuuraimaru shows up for the rescue, then combine with Gokai-oh for the finisher attack, then it'd be complete replay of Tobikage.