I do remember a few.

October 2016-GNW Kankuro

November 2016-GNW Shino

December 2016-I believe it was GNW Choji

I believe January 2018 was Anbu Itachi.

Jan. 2019-I believe Older Konohamaru, I might be off, though.

March 2019-Akatsuki Orochimaru.

Edit-Feb. 2019-New Year Kiba.

I don't remember the exact months for all of these, however.

I do believe Agate Hebihime, Normal Sasuke (For skill books, I think this was Dec. 2017, but I might be off on the year), Jiraiya (Sannin War one), were all in a month.

I believe GNW Kiba was in for September or August, along with GNW Neji (?) filling in for the other month in the year 2016, but I don't know for certain, given I only started playing October 2016.