Most of the existing researches about catch-up strategy have focused on aspects related to technology. The underlying assumption of these researches is that technological, or non-technological differentiation is possible. Most of the defense strategy researches also make the same assumptions that differentiation or price competition is possible in the market. However, there is a lack of research on catch-up and defense strategies where non-technological aspects are considered and differentiation is hard to achieve. When differentiation is difficult, and first mover advantage is strong, firm that has the leading position in the market has the upper hand, and catch-up and defense strategy will be different compared to strategies that can be used in more normal circumstances. This study investigates catch-up and defense strategies when first mover advantage is strong and differentiation is difficult, by conducting a research on the Asian mobile messenger industry. The case analysis results shows that when first mover advantage is strong and differentiation is difficult, quickly entering other new market is the effective catch-up strategy. In case of defense strategy, retaining first mover advantages and reinforcing them is enough to keep the lead in the market. This study contributes to the literature by conducting an analysis on catch-up and defense strategies in circumstances which were not dealt with in the prior researches. Through case analysis, we suggest possible strategies that firms can use when first mover advantage is strong and differentiation is hard to achieve. Further, we highlight that firms should use limited resources more wisely by taking into account all the geographically different markets instead of focusing on competition in just one market.