Interestingly, in precisely the way that facial tissues are called kleenex, regardless of who made them. The Shachihata company actually does have competitors, although the average man in the street probably couldn't name one off the top of his head.
Over the past several months I have had quite a number of custom made rubber stamps made by a shop in Osaka and without hesitation can commend their services to anyone in the need of anything stamp related, whether it be ready-made products or custom made. The variety is wide, the ordering is easy, the quality is good, and the prices are reasonable.
印鑑・はんこの印章事業部門