The Sound of Chains (鎖の音) is the sixth episode of the Re:Zero anime.
After dying to the unknown assailant, Subaru woke up once again in his bed, recalling that no one remembered him after seeing that Ram and Rem were scared of his behavior. He then made his way to Beatrice's library, walking in circles around her while he gathered his thoughts, prompting her to yell at him. The two conversed for a while until she forcefully ejected him from the library, causing him to fall in the bushes outside. He was happy to see Emilia but quickly changed his mind when she told him that Rem had added animal manure as fertilizer. Seeing him struggle to get rid of it, Emilia summoned Puck to help wash it off, to which Puck happily obliged by hitting Subaru with a tornado of water.
A short while later, the three took a break on the lawn, with Subaru play fighting with Puck for his water tornado earlier. The maid sisters soon appeared, informing them that Roswaal had returned, and asked for their presence in the dining room. Breakfast went along as usual, during which time Subaru organized his thoughts, eventually coming to the conclusion that he would have an easier time searching for clues if he asked to live at the mansion as a house guest instead as a servant.
Although he asked to live at the mansion as a house guest, Subaru didn't know where to start investigating and eventually made his way to Beatrice's library. While there he asked her about methods of killing someone by weakening them, to which she told him of curses and her own mana drain, furthering adding that although she returned his mana she wasn't obligated to return lost blood. Subaru didn't believe that she healed him, instead he thought that she was trying to steal credit from Emilia. However, she informed him that the girl didn't have the power to heal him, ejecting him outside seconds later.
Later that day, Subaru still didn't have any clues and was busy contemplating the whole situation when Ram brought him tea, sitting on his bed to drink her own share. The topic of their conversation eventually shifted to children's stories and he told her about the story of the red and blue Oni. Once he finished, Ram voiced her own opinion, and Subaru answered her question by telling her that he would be friends with both Oni. She then asked him about Lugnica's children's stories, causing him to pull out a book, opening it to the stories about the Dragon and the Witch. To his surprise, while Ram discussed the Dragon with him, she refused to even mention anything about the Witch. Leaving the room, she warned him to not mention the story about the Oni to Rem, mentioning that she would probably hate it.
Three days later, on the fourth day, Subaru decided to leave the mansion, thinking that if he left then the others wouldn't be targeted. Roswaal mentioned that he added "a bit more", which Subaru quickly realized was to keep him quiet, though he agreed to not saying anything. A while after leaving the mansion, he was attacked by the unknown assailant, whom he managed to force to reveal their identity. To his shock and horror, the assailant revealed herself as Rem, who then told him that she would've preferred for him to not realize what was happening.