Infiltrate! The Dark Nebula's Castle! (潜入!ダークネビュラの城, Sennyū! Dāku Nebyura no shiro; Nelvana dub: "Infiltrate The Dark Nebula's Castle") is the twelfth episode of Beyblade: Metal Fusion and the twelfth episode of the Metal Saga overall.
Gingka and his friends enter the Dark Nebula's Castle after completely destroying the front door. Shortly after, they come to a big, posh room. They start hearing a voice from the speakers integrated to the small camera that is installed near the ceiling. After a while, Gingka begins to recall that voice from somewhere and he instantly figures out that Merci is the one speaking. The intelligent computer program mocks his previous naivety by saying "Tres bien!" again to fool him. Merci tells them that their road will be one full of obstacles because Doji does not really want them to step further into the building and discover more about Dark Nebula. They however begin running down the multiple long halls. Strangely, they seem to never move forward in their race, even if they are in fact running as fast as they can. Benkei realizes that they are on a giant conveyor belt. Everybody tries to run faster in order to get off that trap, but eventually Madoka stumbles and hits Kenta backwards; they both roll back to the beginning of the treadmill. Next, Benkei trips as well but, having only just told Kyoya that he was keeping up fine, he decides to grab the end of Kyoya's coat, so they both get dragged backwards. Only Gingka is left on the treadmill, and Merci decides to increase its speed; a Beyblade-shooter machine also appears at the end of the treadmill and launches several Beys at Gingka, who quickly fetches his Storm Pegasus and launcher from its case to hit the Beys away from him. Gingka tries to run faster and faster, but eventually Benkei helps him by launching his Dark Bull at the first end of the treadmill; the latter breaks from the excessive wear and a 'hill' rolls towards Gingka; it carries him on safe grounds and destroys the shooting machine. Kenta and the rest arrive at Gingka's side, asking him if he is all right. After being reassured, they decide to go further down the halls, but Merci blocks them by suddenly installing thick walls in their way. Eventually, they find a way; they come across an elevator and decide to take it. To Gingka's dismay though, it only goes up to the third level : Merci voluntarily stopped it there, which means Doji had been planning their adventure in the castle all along. They still decide to advance though, and, in another hall, they find themselves in front of a gigantic, black Beyblade. Merci blocks their way back with a wall again, so they have to fight it. Fortunately, Gingka remembers the trick he used during Merci's false TV show : he wants to make the Beyblade lose balance so it can knock itself out. His technique does not work though, therefore Kenta, Benkei and Kyoya join him in his struggle. All of their Beys get on one side of the opponent and, together, they succeed in defeating it right before it was able to approach them too much. In its failing balance, the black Beyblade broke through part of the wall on the left. Intrigued, they all enter the new room. Upon realising what it is, Kyoya explains that he used to train there for the special program he was following. At first sight, it only seems to contain a Beyblade stadium incrusted in the floor, however Madoka spots a computer, she runs to it excitedly and tries to hack into Merci. Her operation appears to be working and Merci loses coherency fast and its files turn from green to blue, signalling they have become 'good', but it quickly regains some control and both begin fighting for it : Madoka has to turn all the files, red and green, to blue. Meanwhile, Benkei and Kenta stayed behind to fight some trainees that had suddenly appeared with Beyblades to stop them. It seems as if they are all fighting very hard, but in two different dimensions and ways. The two Bladers had almost forced Gingka and Kyoya to get away and leave them behind, but they finally listened to them. On their way, Kyoya and Gingka encounter two Bladers which are almost identical. The newcomers shoot their Blades to challenge the other two: they instantly surpass Pegasus and Leone because of their intense teamwork (for instance, one Beyblade gets on top of the other and, as the other comes into contact with the opponent, the top one bounces on the opposing blade, hitting it from above; also, another of their tactics is that one blade hits the opponent and the other one, which had been 'hiding' behind it, jumps in the air to strike the other spinning top). Seeing that they would have to work a lot to beat the twins, Kyoya tells Gingka to move forward; he will stay there to deal with them. After some time, Kyoya finally uses his wind to defeat them. Gingka reaches Doji's dining room meanwhile, where Doji is waiting for him seated at the end of the long table, with a cup of orange juice. They start talking about L-Drago and how Gingka is determined to face it again. However, Doji plays a trick on Gingka and tries to get him to realize that if he joined Dark Nebula, he would get a lot more power in the end. Gingka, recalling the death of his father at the hands of Ryuga and Dark Nebula, strictly refuses Doji's 'offer'. An intense Beybattle begins and, while Doji appears to be able to counter even Gingka's famous Pegasus Starblast Attack, the latter swiftly grabs the victory because of his Bey Spirit. Just as the battle comes to an end, Ryuga, who had been moving during Doji and Gingka's conversation, clutching his Lightning L-Drago, definitely wakes up and a strange dark purple aura that had been surrounding him in his artificial 'egg' shoots up towards the sky and destroys most of the building, especially the ceiling of the dining room. After recovering from the shock of the unnatural earthquake, Gingka looks up at the top of one of the four walls, and sees Ryuga. The latter mocks him, making Gingka even more furious.
- Gingka and the others break through the front door.
- Kyoya battles Dan Sodo and Reiki.
- Gingka battles Doji and beats him.
- Ryuga and L-Drago awaken.
- Gingka Hagane
- Kyoya Tategami
- Kenta Yumiya
- Madoka Amano
- Benkei Hanawa
- Dan Sodo
- Reiki Sodo
- Ryo Hagane (silhouette)
- Dark Nebula Bladers
- Storm Pegasus 105RF (Gingka's)
- Flame Sagittario C145S (Kenta's)
- Dark Bull H145SD (Benkei's)
- Rock Leone 145WB (Kyoya's)
- Dark Wolf DF145FS (Doji's; Featured)
- Generic Beys (Dark Nebula Bladers')
- Lightning L-Drago 100HF (Ryuga's)
Gingka ( Storm Pegasus 105RF) vs Dark Neubla beyblades= Gingka and Pegsus
- Gingka ( Storm Pegasus 105RF), Kenta (Flame Sagittario C145S), Benkei (Dark Bull H145SD) and Kyoya (Rock Leone 145WB) vs Giant Beyblade= Ginka Kenta Benki and Kyoya
- Madoka Amano (Simulated Digital Generic Bey) vs. Merci (Simulated Digital Generic Bey) = Madoka
- Gingka (Storm Pegasus 105RF), Kenta (Flame Sagittario C145S), Benkei (Dark Bull H145SD) & Kyoya (Rock Leone 145WB) vs. Dark Nebula Bladers (generic Beys) = No Outcome
- Gingka (Storm Pegasus 105RF) & Kyoya (Rock Leone 145WB) vs. Dan (Generic Bey) & Reiki (Generic Bey) = No Outcome
- Kyoya Tategami (Rock Leone 145WB) vs. Dan (Generic Bey) & Reiki (Generic Bey) = Kyoya and Leone
- Gingka (Storm Pegasus 105RF) vs. Doji (Dark Wolf DF145FS) = Gingka and Pegasus
Special Moves used
- Bull Uppercut (Dark Bull H145SD's)
- Lion Wild Wind Fang Dance (Rock Leone 145WB's)
- Starblast Attack (Storm Pegasus 105RF's)
- Darkness Howling Blazer (Dark Wolf DF145FS')
Differences in adaptations