Board Thread:Episode Discussions/@comment-25787298-20160519120227/@comment-26977715-20160521053214

Sarutobii2 wrote: There's no reason Gamamaru wouldn't be effected by the IT. The reason he knew about the event was either because he looked into the Memory Stone that records everything above ground and relearned the events or Kaguya didn't bother wiping his memory, thinking he's just an ordinary toad.

Exactly what I Said 50 post above.

Also, Kishi said that he wants others to continue his work so other media channels can be cannon too.