Having trouble farming them frogs because:

- too many people farming it on one field?
- some areas listed by quest NPCs apparently don't spawn frogs at all?

The thing is, these frogs don't naturally spawn like the other monsters in the field do; you actually need to kill other mobs first before any rain-calling frogs would appear in your area.

Learned it the hard way after i first ran around in a certain non-populated field and found no naturally-spawning frogs; then targeted some mobs out of frustration an lo and behold, a frog or two starts spawning everytime I offed a number of mobs.

Now the question is: would you still want to farm in a populated field and get bombarded with "Wild frogs appear" messages, or would you rather solo/friends hunt in peace on a non-populated one?

Try somewhere that people don't appear, like for example Izumo, Sekigahara.