Tập 4: Bi kịch quá khứ của Saya và bản chất thật sự của kho báu bí mật

4

Saya's father worked oversea as a doctor, and Saya traveled with him, reading a treasured manga. When she returned to her hometown, she met Riki and played soccer with him until it started to rain. On the way home, a mudflow seemingly killed Saya, but not long before she entered the artificial world that Kyousuke created. She died in every scenario of the game, thus making Kyousuke repeatedly "wind back the clock". After a few more attempts of reaching the sixth basement, Saya uses Riki as a decoy in order to defeat Shun. Riki and Saya take an elevator to the sixtieth basement. Once arriving, Saya locks herself in a glass case, revealing that the secret treasure is a biological weapon. After Riki reminisces about his time spent with Saya, he witnesses her shooting herself in the head. After Riki wakes up, Kyousuke tells him that the Darkness Executives "jumped the gun" and that the secret treasure really was a time machine. Saya wakes up as a child and survived the mudflow. She tells her father about the dream that she had. When she recovers, she goes outside to play with Riki as a child. (Source: Wikipedia)