Where does “代走” come from?

代走 (Japanese) comes from Japanese 代, from Middle Chinese 代.

代走 (Japanese): a pinch runner; to run bases as a pinch runner

Definitions

Step	Language	Word	Meaning
1	Japanese	代	substitution; price, cost, charge; shiro, a unit...
2	Middle Chinese	代	—

代走 — Etymology, Origin & Word History | Etymology Explorer