It’s a good thing reinforcements arrive when they do, because Claire’s getting her butt kicked by the three Hunters. It appears that they’re all at a stalemate, until the lead sibling Krovanh starts using more of his Variant power. His sudden power up allows him to break free from Erica’s Everlasting, and the three Hunters fight back. It’s pretty clear that they’re overpowered, although they put up a good fight. (Emilia’s fight in particular was pretty badass.)
It’s only when one of the sisters is held at the end of Emilia’s sword, and Hayato is somehow able to see Krovanh’s memories during their fight, that we get some insight into the Hunter siblings’ background. They were child labour slaves, beaten and treated like garbage until the three were able to escape. They staggered through the desert and Nesat damaged her eye during a fall. Sometime later they met Vitaly, who said that the eye would need to be fixed or else Nesat would go blind. Vitaly offered an experimental treatment which would give Nesat more power; given that all three have Variant powers, we know that Vitaly must have used this “treatment” on all three siblings.
So in the fight of Hayato vs Krovanh, it’s Krovanh’s desire to be free versus Hayato’s dream of a perfect world, where everyone is happy and no one gets hurt. Krovanh continues to falter against Hayato, until suddenly a new dragon type Savage emerges from the lake and starts blowing up the surrounding landscape. Everyone is at a loss for what to do next, until Krovanh makes Claire an offer: he’ll return the stolen Hundreds they took in exchange for defeating the Savage and taking its core. The Savage is so strong that this one core will have enough power to set them free from Vitaly’s control.
However the Savage is much stronger than even Krovanh had estimated. His overpowered attacks alone are not enough to break through its wide-area barrier. When Krovanh’s powers finally dissipate and the Savage knocks him a long distance away with one of its beam attacks, Hayato doesn’t hesitate to use his Variant powers to catch Krovanh before he hits the ground. This is the first tentative step towards the Hunters and the Slayers becoming allies. Krovanh asks Hayato to help his siblings, and Hayato agrees.
Then Claire comes up with the idea of attacking the Savage with long-range beam attacks, and one of the Hunter sisters uses her wrist device to disable to their communications-jamming machine, allowing Claire and Professor Charlotte to share their plan with all of the Slayers on the mission. Their initial attempt ends in failure, and it’s because some of the Slayers were too badly injured right before the attempt and were not able to fire their weapons.
But wait, there’s a possible solution. Char is hesitant to suggest it, but it’s LiZA’s recommendation that Hayato and Claire kiss. Well, you might ask, how will that help their fight? After all at the end of the third episode, we saw Emilia kiss Hayato and he said that administering an inactive virus to an active virus will suppress the active virus. Apparently the opposite is true as well. Hayato administering his active virus will power up Claire’s abilities, although there may be some yet-unknown longterm affects. Claire agrees to take the risk, and despite some initial outrage from both Erica and Emilia, Hayato kisses Claire.
Sure enough, Claire’s power and abilities shoot up, and she coordinates all the Slayers together for one more attack on the flying Savage. At first it looks like their attempt will fail again, but when Claire’s power boosts up into overdrive, the extra surge of power is enough to break through the Savage’s defensive barrier. Hayato is right there, zooming in close to strike the Savage with a finishing blow. He slices the Savage’s head and neck in half, crushing its core, and falls into the lake with its corpse. Emilia rushes into the lake and sneaks in a kiss of her own before rescuing Hayato from the water.
The next day, Claire and Little Garden withdraw from the mission, leaving the rest of the battle up to the other countries and their Slayer teams taking part in the mission. Erica asks Claire about her brother Judar’s intentions, but Claire has no idea either. In the meantime, the Hunter siblings will be staying aboard the Little Garden.
At the hospital, Hayato and the other injured Slayers are recovering steadily. Hayato is unconscious but should awake 
soon, according to Char. Emilia leans over to give Hayato a kiss right as Karen and Sakura walk in; both suspect something fishy, but Hayato picks that moment to wake up, saving Emilia from an awkward interrogation.
At the very end of the episode, we see Vitaly standing in front of some of her creations. Are they Savages? Slayers? Just what is she planning?
My thoughts: Knowing what we learned in this episode about the Hunter siblings and their origins, it’s easier now to see that their fights with Hayato and the others up to this point have been so they can be free. That’s it. When they allowed Vitaly to experiment on them, it put them under her control. Having more Savage cores will give them enough power to leave her and be on their own. That’s pretty noble, even if their methods were questionable.
Funniest scene in the episode? The whole scene where Char suggests that Hayato and Claire kiss. If you watch the shots with Emilia protesting, you can see Erica in the background getting upset as well, while Claudia just looks like she’s enjoying the whole proposition. Also, the subtitles during the actual Claire x Hayato kiss were full of innuendo, just all the innuendo.
Now with the Hunters brought into the fold on Little Garden, the stage is set for a final showdown with Vitaly. Could she have more Hunters ready at her disposal? Or another, stronger Slayer? I can’t wait to see!