I know someone made a list regarding it somewhere, but I haven't been able to find it since, but I believe that when the counter says 7/20, 4/20. and 1/20 (the last of the twenty), you're going to get a rare like Itachi, Kisame, Sasori. I think Guy is a set pull around 10, I'll send the list if I can find it, assuming nobody beats me to it, but this is what I know. Guy is pulled sometime prior to the 14th, or 7/20 pull, the 17th, or 4/20 pull, and 20th pull, or the 1/20 pull, or the final pull. All three of which are rares.

https://forum-narutoen.oasgames.com/page/show-post-26615-1.html

This post says something similar to that., I finally found a post regarding the topic. I think the other pulls are just various materials.

I hope I could help.