side job; side gig
A secondary job done in addition to one's main occupation, often for extra income. Common in modern Japanese, especially in freelance and gig economy contexts.
In addition to his main job, he does web design as a side job.
I earn about 50,000 yen a month from my side job.
Variant with interpunct; less common in everyday writing.
Loanword from English 'side job'.