He wasn't normally conscious of it, but there was one part of his body that was extremely sensitive, somewhere along his back. This soft, subtle spot he couldn't reach was usually covered by something, so that it was invisible to the naked eye. But when, for whatever reason, that spot became exposed and someone's finger pressed down on it, something inside him would stir. A special substance would be secreted, swiftly carried by his bloodstream to every corner of his body. That special stimulus was both a physical sensation and a mental one, creating vivid images in his mind.The first time he met Sara, he felt an anonymous finger reach out and push down forcefully on that trigger on his back. The day they met they talked for a long time, though he couldn't recall much of what they said. What he did recall was the special feeling on his back, and the indefinably thrilling sensation it brought to his mind and body. One part of him relaxed, one part tightened up. That sort of feeling. But what did it mean? Tsukuru thought about it for days, but he was not, by nature, adept at abstract thinking. So Tsukuru emailed Sara and invited her to dinner. He was determined to find out the meaning of that feeling, of that sensation.
Haruki Murakami, Colorless Tsukuru Tazaki and His Years of Pilgrimage
feelings, finger