Overview
Active roster registration (shihaika touroku) is the NPB system that designates players eligible to participate in official first-team and farm-team games, with each club limited to 70 registered players. Active roster players receive uniform numbers between 1 and 99, while development (ikusei) players are assigned three-digit numbers (100 and above) and cannot appear in first-team official games. For a development player to compete at the top level, promotion to the active roster is required. The 70-player cap is a critical constraint in roster construction. Clubs must balance pitchers, catchers, infielders, and outfielders within this limit while also accounting for the foreign player quota (up to 5 on the active roster). Mid-season injuries, trades, and free-agent acquisitions all depend on available roster spots. In recent years, the expansion of the development player system has made it common practice to sign promising young players to development contracts, evaluate their progress, and promote them to the active roster when ready. Earning active roster registration represents a pivotal milestone for a player - it means standing on the starting line of a professional baseball career.