せどり

• Reading: せどり
• Romaji: sedori
• Pronunciation: /se.do.ɾi/

Meaning

Retail arbitrage; the practice of buying underpriced goods at stores and reselling them online for profit.

Originally a term from the used book trade, せどり has evolved into a side hustle where people scan barcodes at stores like BookOff, Hard Off, or clearance sales to find items they can resell on Amazon or Mercari at higher prices. It's a controversial practice — some see it as entrepreneurial, others view it as one step away from 転売ヤー behavior. There's a large ecosystem of せどり tutorials, tools, and communities online.

Examples

1. せどりで月10万稼いでるって言うけど、経費と時間考えたら割に合うのかな。 People say they make 100,000 yen a month from reselling, but when you factor in expenses and time, is it really worth it?
2. ブックオフでせどりしてる人、店員に注意されてたよ。 Someone doing retail arbitrage at BookOff got called out by the staff.
3. せどりの情報商材に騙されて逆にお金失った話よく聞くよね。 You hear a lot of stories about people getting scammed by overpriced reselling courses and losing money instead.

Usage Guide

Context: side hustle communities, social media, business

Tone: entrepreneurial, sometimes controversial

Do Say

• せどり始めたいけど、何から仕入れればいいか分からない。 (I want to start reselling but don't know what to source.)
• せどりって確定申告ちゃんとしないと脱税になるよ。 (If you don't properly file taxes on reselling income, it's tax evasion.)

Don't Say

• 違法な転売を「せどり」と言い換えて正当化するのはNG — relabeling scalping as 'retail arbitrage' doesn't make it acceptable

Common Mistakes

• Not understanding the difference between せどり (buying underpriced items) and 転売 (scalping limited items at markup)

Origin & History

Originally from 背取り — the practice of buying rare books by checking the spine (背) without opening them, then reselling to collectors. Dates back to the used book trade but gained modern meaning in the 2010s with e-commerce and barcode scanning apps.

Cultural Context

Era: Traditional book trade term, modern usage from 2010s

Generation: 20s-40s, side hustle seekers

Social background: Various, popular as a side income stream

Regional notes: Used nationwide. BookOff and Hard Off chain stores are classic せどり hunting grounds.