The Titan's Bride manga volume 3 features story and art by ITKZ.

Kouichi has made the painful decision to return to his world. With their agreement satisfied and his decision made, Caius begins the magical process of sending him back. However, as the process begins, Kouichi watches as Caius’ physical form begins to fade. Unable to help him or ask why, the couple is dragged apart. What is wrong with Caius, and who, if anyone, will be able to help Koichi in his hour of need?!