Kyouso no Musume S01E04 - Episode 4

The death of Aki Nakano (Riko) was rumored to be suicide. Kazuma Yuda (Taiyu Fujiwara), who saw Ichika Yuda (Hana Toyoshima) on the rooftop on the day, asked why he was on the rooftop that day, but he said 'I don't know' and the suspicions only increase.
Detective Hayato Nakano (Shuntarou Yanagi) was wondering about the sudden death of his younger sister, Aki, and began investigating both the incident and the situation. Then, the students will be interviewed, and Kazuma, Ichika, and Sara Kiritani (Mizuki Kayashima) will also be interviewed.
On the other hand, Ichika calls Sara and asks a certain question. Kazuma and Ichika were gradually approaching the 'truth.'
'I believe in Sara.' What is the true truth?