Reddit mentions of Rurouni Kenshin: Restoration, Vol. 2 (2)

In addition to what's already been said there's also a bunch of spin-offs and one-shots:

• a 6 page epilogue from one of the artbooks called "Haru ni Sakura".
  
• a 2 chapter prequel called "To Rule the Flame".
  
• a two volume spin-off called "Rurouni Kenshin: Restoration". [1], [2]
  
• a 2 chapter side-story called "The Ex-Con Ashitaro". [1], [2]
  
• 3 light novels, of which only one was released in English called "Voyage to the Moon World".
  
• a 3 minute long clip from one of the collector's edition box-sets that gives the series a bit better conclusion.
  
• a few special episodes that were not included in the DVD releases, though they're just recap episodes. (No idea where to find these online, sorry.)
  
  There is also a continuation of the manga in the works, but it won't begin until sometime this spring.