An event related to the 20th OP anniversary that took place in in November 2017, consisting of 15 stamina and 20 stamina events. It has moderate difficulty - most teams should be able to clear it. It featured Usopp, Franky, Luffy and Robin (boss) and drooped all of their books, as well as some boosters and evolvers.
Video: [1]
It was followed by Showdown! Straw Hat Pirates Part 2. Should not be confused with the much harder Straw Hat Mission! which occurred around the same time but was much, much harder.