For those like me confused by the difference in chapter numbering relative to the english translation for previous chapters (which goes up to ch.11), it is because chapters 7-9 from there comprise 7 from here, so this would become ch.12 from there, since those use magazine scans and this uses the tankoubon.
The difference in image quality and cleaning is noticeable and it would be great if that translation got edited into the tank scans and added to this to complete the whole thing. Gotta love this artist and straightforward older sister harem stories.