“Guided by Archsage Gotoh, Marth and his companions moved to the “Wyvern’s Dale”, located north of Macedon. The dale is a savage land populated by wyverns and ruled by barbarians. However, Marth had no time to waste. The world's fate was in his hands!”
—Opening Narration, New Mystery of the Emblem
“Under the guidance of Archsage Gato, Marth and the others headed to Macedonia’s north, to the “Dragons’ Dale”. It is an undeveloped region populated with flying dragons, and ruled by barbarians. But, there is no time to stop, because the fate of the world is in Marth’s hands!”
—Opening Narration, Mystery of the Emblem
In order to recruit Michalis, you must have Minerva recruited and alive. Have Minerva "visit" the village by waiting on it before the end of round 15. This will trigger a conversation between Michalis and Minerva. Afterwards, visit the village with Marth, and Michalis will join by the battle preparations in Chapter 22.