Secrets of the Silent Witch, Vol. 4 (manga)

When a trading company visits Serendia Academy to deliver materials, Monica goes with Elliott to greet them, but a small mistake in the company emblem tips her off to the fact that these men are up to no good. Her suspicion prompts the intruders to attack-and just as things start spinning out of control, a new friend swoops in to save the day. Monica can't breathe a sigh of relief just yet, though. Not when even more daunting challenges-ballroom dancing and tea party lessons-lurk just around the corner.