Riddle Story of Devil - Episode 10

Only one final foe stands between Haru and safety, and given that it's the demure Hanabusa surely there isn't too much to worry about?

Indeed, any immediate worries about her hatching a plan look as if they might be unfounded, as an envelope which she hands to Haru contains not an advance notice of an assassination attempt, but an invitation to a tea party - in fact, Hanabusa has even provided