力士

1. Origins, structure, and basic meaning

• Structure: 力士 (りきし) denotes a sumo wrestler. 力士が marks participants in a bout; 力士は topicalizes one identified wrestler.
• Basic usage: Young wrestlers collide in the ring, while a particular wrestler speaks with children after practice.

2. Common pitfalls and similar expressions

• Wrestlers in a bout and one wrestler after training
  • 若い力士が is understood as the wrestlers participating in the action; その力士は identifies one established individual. The term does not merely mean a strong person.