Sssssoooo this was the idea all along, hence why Izumi had to stand on a specific spot and have his hands on Eiji's cheeks. In Eiji's original plan Izumi would have told Demian and Eiji would have defended himself by showing Demian the capture to prove to Demian that it had been Izumi who kissed him and not the other way around. Things didn't go as planned, but ended up on the same place anyway.
I'm sorry for the painful arc ( ' - ' ;;; Demain's brain just showed a blue screen.