When you purchase Japanese knives you should also purchase a minimum of one medium (800-1200 grit) water stone. You can use this stone for minor edge repair, but the medium stone is essential for establishing an edge and for bringing up the even burr necessary for sharpening. If you’re experienced with sharpening Japanese knives, then a fine (5000 + grit) water stone is also a wise purchase.
The fine stone will remove surface scratches created by the abrasive action of the medium stone and create a “mirror-finish” which is highly prized by Japanese and Western chefs alike. We do not recommend the coarse grit (arato) stone for inexperienced users because improper use can seriously damage the blade.