Naruto Online Mysterious Cave: Canyon of River Country

So I noticed there was a boulder that can be broken within the Canyon of River Country in online Naruto games. Once broken it reveals a cave “Mysterious Cave”.
cave online naruto game
Note: You need a ninja “Capable of Rubble” I happened to have Tenten in my team when I first clicked it (she apparently has Rubble). At a guess, Rubble is denoted by this icon  both Tenten and Lee have it (and after testing, Lee is also able to use Rubble on the boulder).
If you do not have a ninja capable of Rubble you will get a notification message at the top of the screen saying so.
As far as I can tell the cave is empty, however it may be that you require a specific ninja in the team to see something in there. I tried putting both Hinata and Neji in my team, since they are the obvious choice for trying to see something.
So if there is some puzzle here, I am stuck with it and wondering if any of you lovely people have noticed this place/gotten any further or just have any more information on it.
Canyon of River Country:
Mysterious Cave Mini-Map:
Location of Boulder/Cave Entrance:  (I’m standing at the entrance)
The boulder before using Rubble:
The boulder after using Rubble:
Naruto Online is one of the most fun MMORPGs! This Naruto game which was launched in 2016 is based on the original Naruto anime. It uses tons of original scenes, characters, skills, and plotlines! It’s perfect for players who like training and collecting. If you like Naruto, don’t miss the chance to play this RPG game!

The Happiest Jinchuuriki