The protagonist Hanazuki is a fifteen-year-old girl who was adopted without parents since she was a child. She has a red line that connects to "someone" in the legendary "Wonderland". At the full moon on the day when I was sixteen, I was led to the "Wonderland" by the ring on the moon pendant that I had found hanging on my body since I was a child. After arriving in Wonderland, I slowly lost my memory of the real world! ... With the help of strangers, intentionally or unintentionally, Huayue found the person connected with her red thread, and discovered another life experience of herself... Who is Huayue's true identity? What happened to Kagetsu before she was adopted by her parents in the real world? How should she face the world she originally lived in and her original self? To return to the real world, you must go back before your memory is completely lost, otherwise you will never be able to leave Wonderland! Between the real world and fairyland, what choice does Hua Yue make? At the end of the red line surrounded by doubts and right and wrong, is that really the happiness that belongs to Hanayue?