The reunion of her childhood sweethearts was once the only light in her abyss.
He accompanies her to get out of the nightmare, actively undergoes treatment, enjoys life, and even proposes marriage. She pulled herself out of the darkness, thinking she could finally touch the light.
But the noose of the original family has never been loosened - the father wanted to take back the house after abandoning his wife and children, and the mother's words "It's all because of you" after she collapsed pushed her back to despair. And the man who said he would protect her for the rest of his life was smiling and letting the little secretary cover his phone screen, missing her last message.
The light had been here before, but turned around and left when she needed it most.
When Hikaru turned around, she was still waiting.