Sugiru Juunana no Haru

From Bliss: Takashi is haunted at night by visions of a woman begging for her child not to be taken away. He sometimes sees strange shadows outside his window, but tries his best to simply ignore them. As his seventeenth birthday approaches, the shadow becomes more and more clear, and the vision more vivid. Slowly, the once kind and caring Takashi becomes indifferent, and eventually cold and biting towards everyone around him. What does this sudden change in attitude have to do with his seventeenth birthday?