Primo Family Arc
The Primo Family Arc is an anime-exclusive arc that details the happenings when Tsuna and his Family that went to the future travel back to the past (except Basil) to get stronger with the help of the Arcobaleno and obtain the Vongola's true power.
Episodes
178 The Primo Family Arrives Apr 3, 2010 
179 Inheritance Begins Apr 10, 2010 
180 The Duty of the Rain Guardian Apr 17, 2010 
181 Furious Bolt of Lightning Apr 24, 2010 
182 Silent Storm May 1, 2010 
183 Aloof Cloud May 8, 2010 
184 Sunny then Cloudy May 15, 2010 
185 The Trap Is Set May 22, 2010 
186 Bewitching Mist May 29, 2010 
187 Memories of Betrayal Jun 5, 2010 
188 Primo's Will Jun 12, 2010 
189 The Family's Resolve Jun 19, 2010