S01E17 — The Lost Treasure

Zumichito tells our three heroes the story of one of his epic adventures. At the time he was a young ninja and a Katana student stole the Jade Dragon from him, a priceless treasure that he was guarding. Just as he'd managed to get the treasure back off the thief - who had taken refuge on a boat on Lake Akayama - a huge monster of a fish attacked them. Zumi had no choice but to abandon the Dragon so as to save his adversary from drowning. Since that day, the treasure has lain at the bottom of the lake.