Dan and ReikiFormerly known as Twin A and Twin B, these two brothers work for Daidouji in Dark Nebula. In the first part of the series, they only act as one of the obstacles in Ginga and Kyouya's way when the two latter beybladers were trying to reach Daidouji and, ultimately, defeat him and Ryuga. Reiki and Dan used their complicity in Beyblade play to battle Kyouya when they still only had two separate, ordinary Light Wheel beyblades. However, as Daidouji gave them Gemios, they really combined their power into one top. They like to mock their opponents, especially when they show their tricks at the beginning of a beybattle and that the other is overwhelmed by them. Together, they eventually become the Killer Gemios Twins and operate closely to ensure victory. In a sense, they bypass the rules by being two beybladers to work with one beyblade, while their opponent is always alone.
Dan, the blader dressed in red, is the more stubborn one; he takes the lead in their duo, always confirms or infirms Reiki's speculations, and otherwise orders his brother to do things. Reiki, who wears a blue jacket, obviously receives the commands and is supposed to simply follow them. However, both of them have the ever popular twin flaw: if they do not agree, they start an argument and get on each other's nerves, which ends up in them being distracted. Kenta used this to his advantage in his match against them.
To fit well with their beyblade, which is based on the Gemini constellation and which illustrates two elements being swirled, Dan has the fire side of their combination, and Reiki, the ice. Together they make strong attacks, either individual or complementary, making big tornados that mix both elements. In general though, they talk a lot but slightly act like cowards sometimes, such as when they told Kenta they would be back to defeat him and rapidly ran away.
Dan comes out as a mature, but arrogant person. He is very patient and waits for the opponent to attack first. He seems to always tell Reiki when and how to do things and this may sometimes upset Reiki. His arrogance is shown when Saggitario continued to spin and he said to Reiki, "This is all because someone wasn't paying attention..." Dan continued to blame Reiki for this and he then said, "My strategy was absolutely perfect, bro." He even calls his brother 'unskilled'. Also Dan is very harsh when he says "No buts, I'm the one who decides." Dan is seen to be a better blader because if Reiki wasn't so hasty, they could have won the battle.
Reiki is immature and hasty. While Dan takes part in Defensive positions, Reiki take the Offensive parts. Reiki always does what Dan tells him to do, but if Dan takes it too far, Reiki will snap. He acts like an attack type blader, as he wants to end the battle as quickly as possible. His immaturity and hastiness caused the twins to lose the battle, and is shown when he says, "I'm not listening!!"
+Kumade Brothers & Dark Nebula Beybladers vs Tsubasa