There were many possible explanations for this question. The following are some possible reasons: 1. Emotional resonance: When you finish reading a novel or anime, you may resonate with the character or feel sad or happy about the plot. This kind of emotional resonance will make you feel more real and intimate, so you will feel lost. 2. A sense of unfinished work: Sometimes, when you finish reading a novel or anime, you might feel a sense of unfinished work. You feel that the plot hasn't developed perfectly, that the characters haven't been fully developed, or that the story hasn't reached the ending you wanted. This sense of loss may be due to your desire to better understand the story behind it. 3. The novelty disappears: When you finish reading a novel or anime, you will feel that the novelty disappears. You once had a strong interest in the story, but as the story ended, your interest would gradually disappear, which would also make people feel lost. 4. Self-exploration: You may feel a sense of self-exploration after reading a novel or anime. You begin to become interested in the characters and plot of the story and try to understand your own thoughts and emotions. This kind of exploration will also make you feel lost because you are gradually understanding your inner world. The above are just some possible explanations. The specific situation may vary from person to person. If you often feel down, you can try to think more deeply about the story you're interested in or communicate with other readers to explore the reasons for this feeling.