The Blue Light

Ryūji Sone returns to the family and begins freeloading off them, unsettling the household. Shūichi senses trouble as the new dynamic creates tension with his mother Yūko and Haruka. The looming presence of Sone marks the start of a dangerous conflict that will push Shūichi toward drastic actions.

Shūichi suspects Sone makes sexual advances toward Haruka one night. He considers removing Sone, but realizes it cannot be done legally because Haruka is his daughter. Yūko urges him to endure the situation until Haruka turns fifteen and can choose her guardian.

After thorough research and experimentation on electrocution, Shūichi designs a plan to kill Sone. He carries out the murder at home, ending Sone's life. The act triggers a cover story that Shūichi hopes will keep him safe.

Police declare Sone died of natural causes, with the death attributed to an illness or unseen factors. Shūichi's alibi is that he was in school at the time, supported by classmates who saw him leave with a half-finished painting and return with it completed.

Haruka reveals to Shūichi that Sone had been dying of cancer, adding a layer of tragedy to his death. Shūichi's sense of guilt and justification becomes more tangled as the truth emerges. The revelation complicates Haruka's relationship with Sone's memory.

Shūichi continues his daily life and begins seeing classmate Noriko Fukuhara. Their relationship develops as he tries to maintain a sense of normalcy despite the hidden crime. He guards his secret while courting Noriko.

Ishioka visits Shūichi at the convenience store where he works and demands 300,000 yen within a week, threatening to tell the police otherwise. The pressure forces Shūichi to consider extreme measures to protect himself.

To silence Ishioka, Shūichi arranges a staged robbery with a fake knife and lures Ishioka into participating. He stabs Ishioka, making the attack appear as self-defense on the security cameras.

Officer Masashi Kano, who previously met Shūichi during the Sone murder investigation, spots inconsistencies in his account and actions. The mounting doubts push the investigation toward catching Shūichi in his lies.

While escorting Noriko home to the train station, Shūichi confesses that he is a murderer. Noriko agrees to lie for him and vows to keep lying in court to protect him.

The police uncover the truth about Sone's death and Ishioka's staged crime; Kano lets Shūichi return home with the condition that he will turn himself in the next day.

After breakfast with his family, Shūichi visits Noriko at her school and leaves a tape recording as a final message. Noriko later confirms she lied for him and will continue to lie in court.

Shūichi commits suicide by steering his bike into the path of a bus, ending his life. The act comes after the weight of his crimes finally catches up with him.

In his final tape, Shūichi talks about his favorite things and what he valued in life. Noriko stops coloring her drawing to listen, realizing the gravity of his confession.