Kappa is an ugly green fishlike guy* that lives in the lake near Mother's Hill. You can marry him if you want, he has an invisible heart. He loves cucumbers, just toss 'em into the lake. He's very ungrateful about it for awhile. You can get Kappa Jewels, but I really don't have any idea how ^^. I think you dig them up in a mine? YAY FOR FUN FACTS: Kappas are also monsters out of old Japanese legends. They look essentially the same and surprisingly enough love cucumbers =D Natsume is so creative!
From your farm, if you head south and cross the bridge over the river at the base of your farm, you'll be in a wooded area with a cabin, which is Gotz's place. If you keep following the path south, you'll see that one part branches off to the left, to the mine and hot spring. Keep following it south, and you'll transfer to another area, with a lake and some trees. Keep following the path as it heads north, and you'll find yourself on Mother's Hill in no time ^^
He's like the Harvest Goddess......the only way to see him is to toss something in the lake for him as a gift. I recommend cucumbers :D Lol and feel free to ask any questions at all...thats what this board is for. Well, besides a place for bored people to waste time on. ^.~
I threw a cucumber in, but it must have been the wrong pond, what pond do I throw stuff in? (it also really helped that I had the blue heart event with Cliff, because he takes you to Mother's Hill and I thought that I was just going to the wrong place.)
It's the big one just above where Gotz wanders around in the mornings...you probably have the right one. Maybe he only accepts certain items? I know for a fact he takes cucumbers, thats all I've ever tossed in XD Maybe look it up on a FAQ?