Before that, after that Webtoon

Jen and York were very close twins, but one day an explosion took their mother's life, and Jen's whereabouts were unknown. Two years later, when York and his father went to visit his mother at the cemetery, he saw someone looked like Jen. He chased after him and found out that it was all in vain. At the same time, a woman with a baby in her hand appeared in the grass in the distance. The baby's face and body were covered with red birthmarks, like burn marks.