In chapter 14, Hime and the others find a mermaid who exchanged her voice to become a human and could not leave a ghost ship because she could not swim and could not call for help. What makes it especially saddening is when the child runs into Hime's arms crying. In the end Hime's brother saves the mermaid after she is forced to return to the sea and makes her semi-immortal.
When Keziah realizes that the reason Emile resurrected him wasn't to cost him his honor as a werewolf but to free the mermaid from Silvia's service. When the mermaid successfully becomes a Flame Warrior, Keziah dies with a smile on his face.
Almost the entirety of episode 10 in the Anime, particularly the ending (doubles as a Tear Jerker).