Kashoku no Shiro

A story of a vow between a pure bride and a demon, in a story "divided by life and death."

"Flower candles" refers to the gorgeous lights that are lit during a wedding ceremony, and refers to a woman who has been engaged and turned around. 

Kiso, a newspaper reporter who pursues a mysterious strange disease that is spreading in the streets, is rescued by a girl who happens to encounter a strange demon. Kiso, who for some reason is strongly attracted to the girl, makes a fierce attack on her, but she was the "candle" that makes a contract with the demon...