- Divine Beast Vah Ruta main quest completed
Tumbo is one of a pair of male Zora children scurrying about Zora's Domain. Talk to him to begin the quest.
Finding five Hot-Footed Frogs is not hard; they are all over Zora's Domain and there is plenty of bodies of water in the Hateno Tower region too (such as the pond in town). The game indicates rainy weather is required, but it does not seem to be. Collect five and return to Tumbo (set the quest as the objective marker to find him) for an Armoranth.
Tip: If you have done the Slated for Upgrades Side Quest and have the Sheikah Sensor +, take a picture of one of the Frogs. You can then set it as your Sensor+ target for help in finding more of them.
Additionally, Beedle at the Dueling Peaks Stable will sell 3 frogs.
Tumbo gave you an armoranth in exchange for five hot-footed frogs. He seemed pretty pleased with the whole arrangement.