ShiroKuro, my first suggestion would be to ask the manufacturer. In fact, you may already have their answer among the papers you received during the sale. But, I'm pretty sure they won't mind telling you again.
My second suggestion comes from information my piano's manufacturer gave me, when I bought my piano. They said, "Clean the keys using a soft, clean cotton cloth, ever so slightly damp, with half a squirt of Windex aimed at the cloth--- never at the keyboard."
Never use a cloth so damp that water runs off the surface and drains into the cracks between the keys--- ever.
You may notice that this advice was for the keys, not the case. BTW, although the keyboard does need to be cleaned occasionally because of oils, shed skin cells, dust that falls out of the air, etc there is no real need to overdo it. I find that once every 3 - 4 weeks is plenty. And also BTW, if you wash your hands before playing, the keys will stay cleaner longer and the touch will be more uniform. There's a big difference in the feel of naked skin on naked key, and naked skin on grubby or gummy keys (which does not look or feel any better than it sounds).
Now, as for the case. Special products? Darlene, who sold me my piano, is all in for cotton baby diapers, washed enough to be really soft. Every day of the world, she knocked the dust off every piano in the store--- there were quite a few; I'm going to guess, close to 100.
Now I absolutely believed her, but I had already become hooked on ostrich feather dusters. The touch is gentler--- almost nothing at all--- using this appliance is very fast and easy on the back, and in the dust palace that is California you need the best help you can get.
You will have to order them. Just search; there are ranches where the birds are raised for such products and taking the feathers does not harm them. The last time I went camping someplace cold, I recall contemplating that humankind has come up with nothing superior to the feather for insulating sleeping bags and really warm down jackets. I need a new duster, though... I've had mine for over 30 years.
Do not even glance at the turkey feather dusters some stores carry. They will not fool your piano or anyone else.
For regular maintenance of your ebony polish finish, I would suggest Cory's Super High Gloss Piano Polish, just as my tech recommended it to me. The full instructions fit easily on the label, and say about what you would think, adding: "Do not spray near strings or tuning pins!"
Back comes our clean, soft, 100% cotton baby diaper.
You can order Cory's products from PW's sister site:
PianoSupplies.com is Piano World's Online Store
Please visit our store today.http://pianosupplies.com
I got the polish from my tech, finally getting a big bottle which it appears is going to last forever. I used to know why ordinary spray furniture polish is not the thing to use on pianos. There's some good reason, but it has slipped my mind. The Cory's comes out as a very thin liquid, and I believe it strips off the old polish and dirt as it lays down a new protective wax layer.
Sorry about the long post, ShiroKuro. You would ask me a piano geek question.