Ninjas hide stashes of equipment and treasure, as part of their stealthy (and healthy) martial arts practices.
There could be one in this video. It might be under a bonsai tree, because that’s a cool symbol to signify the hiding place of a ninja’s stash… but it’s a secret! If you happen to find it, you might find a cool ninja vision stamp!
Treasure hunting like this is called Letterboxing! You can learn all about it on letterboxing.org