Yeah games great, I've got some complaints here and there (*Censored* ANDROID 20) but for the most part the game has been a joy to play.
.... except that one turtle side quest. y'all know the one.
I do not have the game yet, but I feel like that quest has to do with finding a stone that Roshi throws. Unless you literally mean turtle and not turtle as in Roshi as he's associated with turtle.
I'm honestly not sure which Turtle quest he's talking about. Either he's talking about one that is really dumb and super easy...in which case, your guess is close...but not exactly:
Or he's talking about a quest that ends up sending you all over the map and can be kind of a pain in the ass for no good reason:
Neither of those spoilers are really big spoilers of anything. So...feel free to read at your will.