Umm... feels like the rest of the story is missing... No conclusion. argh. This should've been longer. Not sure if the writer/artist ran out of space (in which case they should've paced the story differently) or just wanted to tell this as it is (in which case this is just lazy storytelling, teasing us that Rium has a plan and a trial for the prince and the sister, then we see the sister's smirk and then Rium is like "bring it on" and then... nothing. The only explanation is that the writer didn't make an effort to come up with a tangible idea. Which is, essentially, lazy storytelling.)
Anyway, thank you for the chapter, it was nice while it lasted :'D