You'll wake up in a Nohrian castle, at the sight of two wonderful maids. After the conversations, you'll be sparring with your brother Xander. This is yet another tutorial mission. Xander will not attack nor move but he'll retaliate so you just need to move your character to his position and attack.
After the first attack, Xander will activate a Dragon Vein and reveal a healtile. Move your character there and wait for a turn to fully recover your wounds. Then, attack Xander again. Return to the healtile one more time and attack Xander for the last time to defeat him and complete the mission.
In the later part of this chapter, you'll meet your other Nohrian siblings and you'll be informed that you can travel with them back in the capital to meet with your father which starts in the next story mission.