Board Thread:General Discussion/@comment-1429792-20171130105552/@comment-30535075-20171217135323

In the Bleach Novel: Can't Fear Your Own World II it was stated by Urahara that Ururu and Shinta are not the same species. While Shinta still remains as Unknown, Ururu was revealed to be something similar to Nemu. A creation of Urahara Kisuke. So in the end Mayuri didn't surpass him, he is still one step behind.