relation · person in charge

1. Origins, structure, and basic meaning

• Structure: 係 concerns a connection or an assigned role. 係 is read かかり, and 関係 is read かんけい.
• Basic usage: 案内の係 is the person or role responsible for guidance; 関係 is a connection between people or things.

2. Common pitfalls and similar expressions

• Handing something to the person in charge
  • In 係に申込書を渡す, に marks the person in charge who receives the application.