Pinch runner

[bobbrix]

1st game coming up this Wednesday!!

This is a leftover from last year ....

Coach comes up to me and says, if the next batter (a starter on the lineup) gets on base, I'm putting in a runner for her. Her leg is sore.

Sure enough, she gets to 1st on a walk. Coach calls time and the pinch runner comes in.

Inning is soon over. Player with sore leg trots back on to the field, pinch runner stays on the bench.

I don't see anything in my rule book saying a pinch runner is a substitute or that the player that went to the bench is considered removed.

Is it implied elsewhere?

Can the pinch runner re-enter ?