塁審

1. Origins, structure, and basic meaning

• Structure: 塁審 is read as るいしん and means “base umpire”.
• Basic usage: It refers to a base umpire watching a runner’s feet and a coach serving as the first-base umpire.

2. Common pitfalls and similar expressions

• 塁審が見る / 塁審を務める
  • Use 塁審が見る for the official acting and 塁審を務める for serving in that role. It is a base umpire, not the plate umpire.