For case in point, the "Adventurer's Arc" (a slight arc which reveals how Rimuru got his Adventurer's License, sheds some spotlight on how the Adventure Guild performs, and provides Elen, Kabal, and Gido some additional growth and screentime) is just not protected by the anime specifically, but alternatively receives shown in the first Opening of Season 2, demonstrating Rimuru about to head out with the 3 adventurers, as nicely as his.