Don't listen to C2J6. There has been no news of Kage Treasures coming recently.
Btw, Kage Treasures is the treasures that comes after Sage. It is level locked, but I don't remember at which level. Either 70 or 80. Sage Treasures is supposed to go down to lvl 60 tho.
The rares are, like you'd expect from the name, the Kages, like A, Mei, etc. There is also Susanoo Sasuke, who is a Super Rare, and Susanoo Itachi, who is an Ultra Rare (you can only collect fragments from seal scroll pulls, you can't actually pull the character).
From videos I've seen, you c*so pull characters like Omoi or Mabui or Chojuro, who are regular 3 stars, so I'm not convinced it'll be anytime soon, unless there's gonna be a huge update.