ISBN 978-4801909533. Yosuke Kubozuka (July 5, 2021). "毒を飲ませて殺害し遺体をバラバラに「埼玉愛犬家連続殺人事件」 犯人に殺されかけた男の体験談：じっくり聞いタロウ" [Man claims he was almost killed by the 'Saitama...

(in Japanese). Archived from the original on 3 August 2021. "関根死刑囚が死亡＝埼玉の愛犬家殺人" [Saitama Dog Lover Murders: Death row inmate Sekine dies]. Jiji Press...