For this event you have to progress in the episode until you reach Arlong without any of the Straw Hat Pirates fleeing. The Straw Hat Pirates include Luffy, Zoro, Nami, Sanji, and Usopp. Although you will be playing as one of them, so you only have 4 to look out for. Usopp is the one you will have to keep a close eye on. He will be moving around a lot in this episode in order to destroy the various waterway switches, and he encounters a lot of enemy forces along the way. Make sure to protect him and be on the lookout for any other Straw Hats that might be in trouble so that you can help them.