This is a Doubles-Only technique in which both players become fully synchronized and move as if they were one; breathing as one and knowing exactly what their partner's next move would be. It is said that doubles players could not go to the top of the pros without 'Synchronization'. This Technique is not limited to two-players though as shown by Niou Masaharu when he used the technique to synchronize with The Mutsu Twins.
This first time a player enters this state, similar to Muga No Kyouchi the players mind is completely blank and is playing unconscious unaware that they have actually activated Synchro.
It should be noted however, that Niou Masaharu is able to effortlessly enter Synchro when playing Doubles with a player that has achieved the ability to access Synchro at will with their partner. This is because as long as Niou uses his Illusion to become a player that is part of a Synchro pair such as Kikumaru Eiji or Mutsu Yuuho, then Niou can Synchronize with them. For example, Mutsu Yuuho can use Synchro when paired with his twin Mutsu Yuuma, therefore if Niou uses his Illusion to become either Yuuma or Yuuho, Niou can enter the Synchro state with them.
- Oishi Shuichiro with Kikumaru Eiji or Niou Masaharu.
- Kikumaru Eiji with Oishi Shuichiro.
- Issa Washio with Suzuki Shun.
- Shun Suzuki with Washio Issa.
- Mutsu Yūho with Mutsu Yūma or Niou Masaharu.
- Mutsu Yūma with Mutsu Yūho or Niou Masaharu.
- Niou Masaharu with Oishi Shuichiro, Atobe Keigo, Mutsu Yūma or Mutsu Yūho.
- Atobe Keigo with Niou Masaharu.