Customization systems have incarnated the notion of co-creation and provided a wide variety of customized products which fit individual customers’ needs. However, most customized fashion items are no more than modified products based upon existing products and, therefore, satisfy only expressed needs. In contrast, mass-production systems can offer more innovative fashion items satisfying latent needs, though they may not fit individual needs in detail. To investigate the relationship between the type of market orientation (responsive vs. proactive market orientation) and the type of production system (mass-production vs. customization systems), we conduct a consumer survey regarding four types of fashion items (sneakers, business shirts, belts, and underwear). The results of ANOVA showed that fashion categories in which customers have the needs for responsive market orientation have much potential for developing customized products, whereas fashion categories in which customers have the needs for responsive market orientation have less potential for providing customized products. The results also showed that fashion categories in which customers have the needs for proactive market orientation have much potential for providing new, innovative (mass-produced) products, whereas fashion categories in which consumers have proactive market orientation have less potential for providing new, innovative (mass-produced) products. Firms should emphasize on the responsive market orientation if their customers perceive much potential for developing a customization system in the category; firms should emphasize on the proactive market orientation if customers perceive much potential for offering new, innovative products under the previous mass-production system. If there are potentials for developing both innovative mass-produced products and customized products, firms need ambidextrous market orientation.