Thanks for the chapter!
Really scummy friends for selling her out for money after all the life and death experiences they must have had. Surprised the Cornelia Kingdom accepts someone being made a slave just because a magic slave collar is put on them. In LN it shows that collars like that are rare and will kill the slave if try to remove it by force hence the Control Device needed on page 11, although seems Eleanor doesn't want to remove the collar and her link to MC. Even if willing seems odd she knows how to act like a slave and know the standard treatment of slaves considering was only a slave for a few months (most of which was spent terrified and recovering from shock and trauma of her sisters' and friends' betrayal along with being turned from a person into property as far as the public see her,) and MC first buyer. Then again she might be a closet pervert finally blooming into the role of being the sex slave of a (perverted) kind master who owns her but still cares for her. Guess will just have to see how things go.
@AFresherPerspective Link to LN here: https://www.novelupdates.com/series/an-s-rank-adventurer-me-along-with-those-girls-who-are-slaves-form-a-slaves-only-harem-guild/
@kowoyoshi Sisters might have been too sisterly and/or evil to go for death. As in wanted her out of way but didn't want to kill her (either sisterly affection preventing them from staining their hands with her blood or so evil wanted to humiliate and put her through hell for getting in their way rather than a quick kill,) so went for slavery. Also, if she died and the King found out about it, like her 'friends' were caught getting rid of the corpse, he'd likely have found out about their involvement and for them at best remove them from becoming queen, or at worst execute or imprison them for life. This way they can honestly say she's still alive as far as they know, and haven't done anything to have her killed.