A salaried employee's side-hustle secondhand-clothing shop hits ~¥3M in year one, profitable every month on 5-10 hours a week

Side-hustle e-commerce revenue write-ups tend to circulate as a bare annual or monthly figure with nothing to check it against. What Wakabayashi published on note about the first year of an online secondhand-clothing shop comes with three denominators attached: per-channel actuals, cost ratio, and hours worked. It’s one full year (keeping a day job, working out of a single room at home, 5-10 hours a week) that added up to nearly ¥3 million in annual sales.

Lining up a year of sales

The author states 2024 full-year sales across the three channels (BASE, Mercari, and Yahoo Auctions) as “just under ¥3 million.” Actual figures are disclosed for three individual months:

The channel split is stated as “BASE 6 : Mercari 3 : Yahoo Auctions 1.” The author writes: “BASE generally runs around ¥100,000/month. Mercari runs about half of BASE’s sales each month.”

Worth cross-checking here: the three disclosed months’ BASE sales are ¥75,970, ¥178,090, and ¥249,270 — two of the three exceed the self-described “roughly ¥100,000.” Dividing annual sales of just under ¥3 million by 12 gives a monthly average around ¥250,000. At a 6/10 split, BASE alone would work out to roughly ¥150,000/month. The actuals run higher than the self-perceived figure, and month-to-month swing is significant too. Combined, the strongest month is roughly 2.85x the weakest. For BASE alone, roughly 3.3x. Side-hustle e-commerce revenue, on this evidence, does not smooth out.

What’s sold, and how it’s run

The product is secondhand clothing, run solo out of a single room at home, at 5-10 hours a week (roughly 1-2 hours a day). Sourcing combines monthly or bimonthly in-person buying trips with online purchasing.

The full workflow is listed by the author: washing, steaming (ironing), e-commerce admin, promotion (social media), pricing, sourcing, inspection, measuring, photography, listing, shipping, 11 steps in all. She describes this as “a fairly demanding, tough line of work.” Promotion runs through Threads, X, and note.

The profitability rule is stated explicitly too: cost ratio is set at about 35%, translating to “roughly ¥130,000 in profit on roughly ¥200,000 in sales.” The business has been profitable every month since launch.

No dramatic turning point. What worked was a fixed pricing rule

There’s no moment in this case where the trajectory visibly changed. The business has been profitable every month from the start. No month spiked, and there’s no record of numbers jumping before-and-after any particular tactic. Even across the three disclosed months, the figures move up and down within the same band.

So what made this year work traces back to the initial design, not to any single turning point. And among those design choices, fixing the cost ratio at about 35% is the one doing the most work.

This isn’t only about margin. It changes how sourcing decisions get made. Without a cost-ratio benchmark, buying decisions in the field become aesthetic judgment calls, “is this piece nice?”, inviting hesitation and eating time. Once the benchmark becomes “can I buy this at a price that lets me sell it at roughly 3x,” the decision collapses to a binary yes/no. Sourcing is the highest-friction decision in the whole workflow, and turning it into a threshold check is arguably the single biggest reason the operation fits inside 1-2 monthly buying trips and 5-10 hours a week.

What makes the 5-10 hour week work

Another factor at play is the channel mix. BASE, a self-hosted store, is the primary channel (60%), running alongside Mercari (30%) and Yahoo Auctions (10%).

This split directly reflects the trade-off between fees and acquisition cost. Marketplaces charge higher selling fees but deliver ready-made search demand without requiring your own acquisition effort. A self-hosted store has lower fees but requires you to generate your own exposure. Lean entirely one way and you either lose margin to fees or lose time to acquisition. The 6:3:1 split sits deliberately between those two extremes.

The nature of the product itself also feeds into the low hours. Because each piece is one-of-a-kind, inventory never duplicates, but an unsold piece is a pure loss. However, because per-piece sourcing cost is small, the downside of any single bad call is small too. The 35% cost ratio only works on top of this “small misses don’t matter” structure.

Re-checking the “¥130,000 in profit”

The author’s stated “roughly ¥200,000 in sales, roughly ¥130,000 in profit” checks out against the 35% cost ratio: ¥200,000 sales, ¥70,000 cost of goods, ¥130,000 remainder. But it’s reasonable to assume this ¥130,000 is gross profit after subtracting only the cost of goods. It likely doesn’t yet account for platform payment/selling fees, shipping, packaging materials, or cleaning/consumables. Marketplace fees in particular are non-trivial, so actual take-home is likely lower than ¥130,000.

Running the annual math: at roughly ¥3 million in annual sales and a 35% cost ratio, annual gross profit is roughly ¥1.95 million, or about ¥162,500/month. Dividing that by hours worked (5-10 hours a week, or 20-40 hours a month) gives a gross margin of roughly ¥4,000-8,100 per hour. Fees and shipping would pull the effective figure down further, but as a side-hustle hourly rate, that’s not a bad band. Conversely, this also shows the business is capped by available hours.

The one-person ceiling

The limit is one the author names herself: “since I’m doing everything solo, I feel this is roughly the ceiling for this approach as currently structured.”

The reason lies in the step count. Most of the 11 steps happen per piece: washing, ironing, inspection, measuring, photography, and listing all scale with unit count. Doubling revenue means doubling unit count, and doubling unit count means doubling the work. Short of raising prices, hiring help, or outsourcing/automating steps, there’s no way to break that proportional relationship. As long as the 5-10 hour weekly ceiling holds, roughly ¥250,000/month is structurally the cap.

The other risk is revenue swing: ¥362,000 in a strong month against ¥127,000 in a weak one. Sourcing runs on a fixed 1-2-trips-a-month cycle that occurs before sales are known, so inventory builds up even in slow months. The 35% cost-ratio rule also functions as insurance, keeping that inventory risk within a tolerable range.

What transfers, and what doesn’t

What’s reproducible is the systems side: fixing your cost ratio upfront to make sourcing decisions binary, running a self-hosted store alongside marketplaces at a set ratio, deciding your available hours first (5-10 hours a week) and sizing the business to fit. Keeping fixed costs at zero by working from a room at home. None of these require capital or a specialized skill. The secondhand-dealer license required to operate is also a low administrative hurdle.

What’s hard to reproduce is the sourcing itself. Wakabayashi writes that her reason for starting was, ultimately, “loving it matters most,” and closes with, “getting to earn money doing something you love is the best feeling.” A monthly in-person buying trip is, for someone with no interest in the work, pure labor time, but for someone who loves it, it’s absorbed as an extension of a hobby. One plausible reading of why 5-10 hours a week works out at all: the most time-consuming of the 11 steps isn’t registered as a cost to her at all. The same applies to her eye for pieces and her sourcing routes, neither is something anyone starts with in year one.

The most useful number this case offers for anyone evaluating side-hustle e-commerce isn’t the ¥3 million annual figure. It’s the combined package: 35% cost ratio, 5-10 hours a week, roughly ¥162,500 in monthly gross profit, and the self-reported “this is the ceiling working alone.”

Related reading

• Running a rental-space business — another individual starting on small capital; a comparison point for where the hours-to-revenue relationship breaks.
• 4 months with a food truck — a small business capped at one person’s hands and one set of inventory, offering a contrasting take on where the ceiling sits.