One campus
Sinchon is the west daytime circle, not the opening act of a Hongdae night. The Ewha wall or Yonsei — one campus, not both. You do not owe the Hongdae main street at night. This circle has no separate market. Do not detour to Mangwon just to eat; that dinner belongs to the Hongdae axis. Eat in Sinchon and stop. Do not stack a full day here on a full Hongdae night. In rain, the Ewha campus link or indoors by the station. Save the wall and the grounds for a clear day. Leave from Sinchon station once the campus is done. The Hongdae main street, if you want it, is another night. Do not attach it to the back of this afternoon.