The Defense Four are detained to their homes for a week due to the events of the previous episode. Takayama receives a letter with the text "Today could be your last day." Takayama calls Sakurai for assistance. Sakurai does not answer so he instead calls Haruka. Sakurai spots Haruka on the way to meet Takayama in Akihabara. After seeing the letter, Haruka suggests the sender could be an accomplice of the bomber of the Ashio Line. They are interrupted by a JNR mascot, Tsubarail and move to a different location. Sakurai calls Takayama back but during their conversation, a gust of wind surprises Sakurai and her phone breaks when she drops it. Sakurai spots them again while walking out of the phone repair shop. She shoots Takayama out of jealousy. Haruka and Takayama mistake this for a sniper and continue running away from Sakurai, who they mistake for the accomplice.
足尾線での不始末の責任を咎められる形で第四警戒班は謹慎処分を受ける。 家でのんびりと過ごしていた直人だが一通の手紙を受け取ったことでムードが一変――それはなんと暗殺予告だったのだ。相談しようとあおいに電話をかけるが繋がらない。
はるかは、スポーツジムで体力強化に努めているところだったが、直人からの電話を受け、慌てて直人のもとへ駆けつける。
國鉄秋葉原駅近くで落ちあう二人。二人は街を逃げ回るはめになるのだったが――
El Cuatro de Defensa son detenidos en sus casas durante una semana debido a los acontecimientos del episodio anterior. Takayama recibe una carta con el texto "Hoy puede ser el último día." Takayama llama Sakurai para obtener ayuda. Sakurai no responde por lo que en vez llama a Haruka.
