R4, aka Valghis, is the final model in the R-Series, and is the most powerful.
He has pitch black hair similar to Rodea's in style with white strands framing his face. His eyes are rimmed with a dark shadow and he is almost always smiling with wicked intent. An 'X' shaped marking is on the bridge of his nose, although the other half of his face is never seen.
Valghis has the traditional sky soldier uniform with some modifications, such as a rope over his shoulders, a higher collar and extended length. It is black in color and has a blue trim, giving him a sinister appearance. His gloves are not black like the rest of the R-Series and are a lighter gray instead. He appears to be missing the tailpiece the rest have.
Valghis is immensely proud of his status as the Naga Empire's most technologically advanced sky soldier, and his arrogance is matched only by his ambition. When he first encounters Rodea, he seems fine with letting him go back in time to potentially defeat him. During their fight, he begins to get more and more cocky, possibly due to the pressure of fighting the most experienced R-Series model.
Though Valghis swears loyalty to the Naga Empire, he is loyal to himself first and foremost, and will do whatever it takes to achieve his true goals.
He believes that coexistence between humans and robots is impossible.
Valghis is considered the crowning achievement of the R Project. His combat abilities are state-of-the-art and his intelligence is said to rival Emperor Geardo's. For this reason, Valghis was entrusted with the other half of the Key of Time while he carried out his mission.
He seems to have an ability to use information based on past events to predict possible future outcomes of a situation, as he constantly makes predictions, and during his fight against Rodea, he claims he has predicted his every move. He also states that him and Rodea are the only two models on which the Key of Time can be used, as the other R-Series models refused it.
He apparently has the ability to paralyze people and robots just by snapping his fingers. He can also unleash a large number of large energy beams.
1000 years ago, after Naga's first attempt to invade Garuda failed, Valghis was entrusted with the half of the Key of Time that was in Princess Cecilia's possession. He and the rest of the R-Series (sans Rodea) received the mission to retrieve the other half, 1000 years later when Garuda would be accessible again, and open the R-Gate to bring Emperor Geardo from the past to the future. However, unlike the other units, Valghis was apparently unhappy with being bound to an order for 1000 years.
Valghis shows up, walking in mid-air and applauding, after Rodea stops all the Chronos Towers. He paralyzes Rodea and Ion and takes Rodea's half of the Key of Time, then combines it with the other half he is carrying to reconstitute the full Key. He shoves the Key in Rodea's chest and turns it, opening the R-Gate that leads 1000 years in the past.
Valghis explains that Naga will summon machine soldiers from the past to invade Garuda. Rodea claims he'll stop them, and Valghis, having expected this, encourages him to go back in time to try to save Cecilia and defeat Geardo.
Valghis crosses the R-Gate and waits for Rodea in the throne room of the Naga fortress, secretly expecting Rodea to defeat Geardo, which is what happens. With Geardo dead, Valghis plans to create a machine empire on Garuda. As expected, Rodea refuses to let him do that, and they fight. Valghis is beaten, though he had envisioned it; he seems grateful that Rodea has freed him and the others. His final words are corrupted as he shuts down, dropping the Key of Time.
Valghis is briefly seen again in the new future, flying around as Rodea reunites with Ion.
- Valghis' name (in Japanese ヴァルギアス, Vuarugiasu) apparently comes from Barghest (in Japanese バールゲスト, Varugesuto), a monstrous black dog from Northen English mythology.
- Valghis is the only antagonist in the game to call Rodea by his name (rather than "R0" or "big brother")
- In the Wii version, when playing as Valghis, he gets a tail (similar to that of the other R-Series units)
- During his first appearance after Rodea's fight with Odeon, he already has Princess Cecilia's half of the Key of Time. Though some may spectate that this means Valghis himself went to get the key from Cecilia's body, the official art book states that he was entrusted with her half, likely meaning that a less valuable machine soldier was sent to get it instead.