Ryo-tas demonstrated on Yuuta how fast spirit particles move through time. Gamo-tan approved!
A long-lost daughter of Tesla shared Ryouka's body. She was much more serious than the usual Ryo-tas we see.
However, since they had shared memories for so long, Aveline Tesla took on many of the, ah, endearing mannerisms we've enjoyed from Ryo-tas over the season.