Overview
Active roster registration (shihaika toroku) 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 of no more than two digits, with 0 and 00 also permitted, 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. Registration is a prerequisite rather than a ticket to the top level: to actually appear in a first-team official game, a player must additionally be placed on the first-team roster (shutsujo senshu toroku). The 70-player cap is a critical constraint in roster construction. Clubs must balance pitchers, catchers, infielders, and outfielders within this limit while also planning how foreign players will be used. No cap applies to the number of foreign players a club may carry on the active roster; the limit falls on the first-team roster instead, so how many to hold under contract and how many can be used at the top level are separate decisions. 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.