あし はや
ashiga hayai

i-Adjective
Expression

1. to be fast at walking and running

i-Adjective
Idiomatic Expression

2. to be quick to spoil (of foodstuffs)

はや かえった ほうがいい、暑 あついから。サバは、生 くされとも われるくらい あし はやい。
hayakukaetta hōga ii atsuikara. sabawa iki kusaretomo iwarerukurai ashiga hayai.
It's hot, so you'd better head back quickly. Mackerel goes off so fast that they coined 'fresh-looking rotten fish'.