It was summer in Japan, but for Rina Okada that meant cram study. She couldn't go on with the rest of the family on their annual trip. School came first, but that was partly an excuse. She was also at the age where she was eager to spread her wings. Be separate from the family. She would stay home while they vacationed. No brothers to mind. But it wouldn't be at all like she thought. Trip day arrived. Rina saw her family off and went upstairs to study at her desk in the empty house. After a while, she heard a rustling sound from the first floor. She assumed it was her family come home to grab a suitcase or something. She went downstairs. "What happened?" she said unguardedly. "Did you forget something?" Nobody was there, so she went to the entry. How could she have known what a terrible person was waiting on the other side?