-( Story related, cannot be missed )-
There are only four missions to the third chapter, in which we finalize our roster with the entire Straw Hat crew. They are:
Episode 1: The City of Water, Water 7 (CP9 & Robin, part 1)
Episode 2: Pirates vs. CP9 (Enies Lobby, CP9 & Robin, part 2)
Episode 3: Fist of Love (CP9 & Robin, part 3)
Episode 4: Adventure on Ghost Island (Thriller Bark)
None of these are particularly threatening and require any real direction to be pointed to. Just remember: S ranks can't be obtained in Easy Mode, so if you're trying to fill up the Legend Diaries, keep that in mind. Oh, and make sure you wallop the final boss of each mission using a Special Kizuna Rush, to avoid having to try and get it at a later time, on a higher difficulty, where they may fall faster or slower (depending on your characters and their levels).