Caius x Kouichi
Titan Prince Caius summons Kouichi to his world through strong magic where Kouichi is meant to be his bride. Kouichi isn't keen on it happening but Caius is kind and gentle and wins him over so he agrees to stay and fulfill the prophecy, becoming Caius' bride despite the obvious lack of plumbing he has for it. They're in love and happy and hope that that will be enough.
The Titan's bride