Scent of Danger! The Seventh Member is Nico Robin! One Piece: Wan pîsu : Season 4 Episode 130

The Marines fail again to catch the Straw Hats. After escaping from Marines, Nico Robin (Ms. All Sunday) appears from inside of Straw Hats ship. She manages to persuade the crew to let her join. Pell is seen at the end standing over his own grave.