Source: Kuroinu: Kedakaki Seijo wa Hakudaku ni Somaru Episode 4 音楽 / Music: Martyr / Guiding Ahead Boss Battle Theme Arknights OST Part 1 - Pain: https://www.iwara.tv/video/yzw8zsqo7of9wdmzd Part 2 - Battle: https://www.iwara.tv/video/qoj9oijm0qiarz28d Part 3 - Punishment: https://www.iwara.tv/video/GumpPKfg8p4XZh