User blog comment:B214/Question and Answers 4/@comment-24502975-20141102214513/@comment-114.4.23.111-20141103011816

@Gary they were kissing, making a mistake like wrong input of formula is probable.

That's exactly what i am thinking. The use of teleportation circle in the current timeline is probably different from what it was due to the research in magic.So the use of formula incorporated with demonic power is a likely theory how the teleportation works.

@B and Jop If knowing the location is the only thing to use teleportation for devils, then the incident when Euclid not being able to escape because his teleportation was altered would never happen. So a formula is needed for using teleportation circle. Anyway i always assume that the fliers thing as a tracking device.

@Obey Demonic power is also needed though, because just like what happened to Issei in Vol 1 IIRC, for not being able to use teleportation due to his insufficient demonic power