A week or so after coming to Hoshido, Queen Mikoto is planning to make a grand public announcement to tell everyone that Princess Corrin is back. As they're milling about in public, an extremely creepy man you'd think security would have kept out starts to cast a spell of some sort.

The sword that King Garon gave to Corrin as a gift suddenly goes flying straight for the creepy man, allowing him to cast his devastating spell that tears through the city.

Emm-- Mikoto dives in front of Corrin and protects her from the attack, sacrificing her own life.