Olympics Sports Trainer, Meg Thompson, had never even heard of an otome game, so when she died in Japan during the Tokyo Games and was reincarnated into one in error as the minor character, Briar Bell, she might have unintentionally messed just about everything up for the true heroine...
Whether it was her befriending villainesses, or hanging out with capture targets, from the moment she was born she was setting the plot careening off course. (although if you ask her, the original storyline was stupid and hopeless to begin with #SorryNotSorry)
The Heroine was supposed to seduce this medieval-esque kingdom's most eligible bachelors in order to use the power of their love to stop the encroaching demon army from destroying humanity with her heart magic. Playing the role of 'heroine' was another reincarnated woman named Sakura, a hardcore Japanese otaku who had previously been hit by a truck in a tale as old as time.
Whether it is the fault of Sakura's social ineptness (as Briar would claim) or from her own interventions, humanity is now heading towards total decimation. Seems like she'll have to brush off her coaching skills and get this royal army into fighting form.