The Green Flames

(from ebookjapan):

The older sister, Isabella, eloped with a man her father disapproved of. After that, Carol, the younger sister, came to a town called Leia in the middle of the desert to see Isabella, whom she had not heard from for six years.

However, when she finally sees Isabella, she is a different person.

The whole town of Leia is enveloped in a gloomy atmosphere, and the people are scared of something. And what is the secret of the green forest on the east side of the town...⁉

In addition to "The Green Flames", "White Shadow Man" is also included.