3 Last Missions on Summer event I don't speak/read japanese, and I know that the upper missions on the summer event drop more of those gold tags and the bottom ones drop more...goldfish bags? (I recall it's beach trash, but I don't know which.)

What are the last 3 missions after clearing the limited events good for? (The level 50, 60 and 70 with Andvari, Goemon and Volos respectively) Challenge quests?