Responses
Yes, in a previous chapter Caius told Koichi that he basically punched a hole in the fabric of space-time to summon him. Something like that undoubtedly has major consequences because he was unable to complete the familiar contract and had to do the return summons. It would also take a massive amount of energy, it's more like he expended all his energy sending Koichi back.
so it's a one way ticket? and It will harm caius bc he doesnt have enough power without his bride or smth?