Would a Japanese collector use an app like this?

I'm building a small iPhone app for people who collect things — records, retro games, comics, watches, cards. Not for reselling: for keeping. You photograph what you own, the app identifies it, and you get a shelf you can look at, lend from, insure, and eventually sell from if you want to.

The data says Japan might be the best market in the world for this idea, and that nobody is serving it. But the data can't tell me whether the app would actually make sense to a Japanese collector. That's what I need help with — three questions, honestly answered, from someone who knows the culture from the inside.

This is a research favour, not a job, and I've kept it deliberately small. What I can offer back is at the end.

Question 1 — Where does a Japanese collector look to find out what something is worth?

In Europe and the US there are two or three websites everyone trusts for prices, and they're trusted because they show real completed sales rather than a guess. My app is built on quoting those sources by name. I don't know what the Japanese equivalents are, or whether they exist.

• If a friend showed you an old record, game or figure and asked "how much is this worth?", where would you actually look? Name the sites or shops.
• Which of those do collectors trust, and which are just places to buy and sell?
• Is it different depending on what's being collected? Records vs games vs cards vs figures.
• Do any of them publish past sale prices publicly, or is that information private?

What a good answer looks like: a handful of names with one line each on who uses them and whether they're trusted. Links are enough — I can navigate a Japanese site with a translator, I just don't know which ones matter.

Question 2 — Do Japanese collectors catalogue what they own, and where?

Elsewhere, serious collectors keep a list — on a website, in a spreadsheet, in an app. My whole product assumes that habit exists. If Japanese collectors don't keep lists, or keep them somewhere I've never heard of, that changes everything.

• Do people you know keep a record of their collection? Where — an app, a website, a notebook, nothing?
• Is there a well-known Japanese service for this, for any category?
• Do collectors show their collections to other people? Where — social media, forums, in person at events?
• And the blunt version: does the idea of an app that keeps a private list of everything you own sound useful, or slightly strange?

What a good answer looks like: your honest impression plus two or three examples. "Nobody does this" is a completely valid and very useful answer.

Question 3 — How do two of my main selling points read in Japan?

Two things I say about the app work well in France and Germany. I have no idea how they land in Japan, and they might land badly.

• "No account. Your data stays on your phone and never goes to our servers." In Europe this reads as trustworthy. Does it read as trustworthy in Japan, or as unfinished and amateur — like a real company would obviously have accounts?
• "Pay once, €30, no subscription." Is a one-time app purchase normal and appealing, or does a subscription feel safer and more legitimate?
• Is there anything about a small foreign app handling your possessions that would make you hesitate?

What a good answer looks like: a gut reaction, not research. Your first instinct is the valuable part — please don't be polite about it.

A small bonus question, if you have the energy

What word would a Japanese person type into the App Store to look for something like this? Not the correct translation — the words people actually use. If there's no natural word for it, that's worth knowing too.

What I'm not asking for

• Not a translation of the app. That comes much later, if at all, and it would be paid work.
• Not a market study, a slide deck, or anything formal.
• Not a survey of other people. Your own view and your own circle is exactly the right size.

Format, effort and timing

Bullet points in an email or a shared document. Links and screenshots are more useful than prose. Rough notes are completely fine — I would rather have honest fragments than a tidy report.

Write in Japanese if that's easier and faster for you; I'll work through it. English or French are also fine, whichever costs you the least effort.

I'd guess four to six hours in total, spread over two or three weeks. If it's taking longer than that, stop and tell me — it means I asked badly.

What I can offer in return

This is an exchange, and I want to be honest that my side is time and attention rather than money.

• Language and communication. Regular conversation in French or English, as often as suits you. I'll happily correct writing, help with emails, applications, a CV, or preparing for an interview.
• Practical help with life in France, if you're here — administration, phone calls, the paperwork that's genuinely hard from outside.
• A look inside how a product gets built. If it interests you, I'll walk you through the design work, the business plan and the competitive research. It's real material, not a demo.
• Credit. If the app ever ships in Japan, your name is in it, and I'm glad to be a reference for you.

And if this turns into something bigger — real localisation work, ongoing advice — then it becomes paid work with a proper agreement. I'd rather say that now than let it drift.

One last thing

The most useful person for this is a collector — of anything at all. If you collect something yourself, most of these questions you can answer from your own experience, and that's worth far more to me than research.

If any of this is unclear or badly framed, please say so. It's very likely I'm asking the wrong question somewhere, and telling me that is itself the most useful answer.