This is definitely just a manga to pass time... I can clearly see the story which she meet...

This is definitely just a manga to pass time... I can clearly see the story which she meets her sister, gets kidnapped by her sister's partner, the duke hears the news of MC being gone and then he realizes that he doesn't want her to dissappear and loves her blah blah blah they live happily ever after

The sister's M.O. will be definitely be because MC is missing so she'll have to fill in MC's shoes and marry the duke