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All the Code Was Written by AI! And Almost Everything Else, Too.
All the Code Was Written by AI! And Almost Everything Else, Too.
This is Cupbearer Project’s very first app—a rather memorable milestone for us. Using your iPhone’s step counter, you can walk the 53 Stations of the Tokaido, all the way from Edo to Kyoto. A virtual journey, quite literally!
Actually, I came up with this idea about 20 years ago. Back then, though, iPhones didn’t exist, so I would have had to go out and buy a pedometer myself. And buying a pedometer just for that? Well… you know. (Would you really want to?) Besides, I couldn’t write a single line of code, so I had no choice but to give up on the idea.
AI Does a Pretty Good Job!
ところが，AIの登場で状況が変わりました｡プログラミングのシロウトでも，AIにコードを書いてもらえばアプリが作れるようになってしまったのです｡で，ChatGPTを使ってコードを書いてもらいました｡当時のGPTはそれほど賢いとは言えませんでしたが、それでもこのアプリを作るには十分でした｡
ちなみにこのアプリの作成開始は2025年8月からでした。
さらにAIがすごいのは，イラストも描いてくれるということです。
Introducing Edonosuke and Ukiyo Komachi!
At first, I thought it would be enough to display ukiyo-e prints of the 53 Stations of the Tokaido according to how far you had walked. But once I actually made it, I discovered something rather disappointing: it wasn’t much fun. Partly because the iPhone screen was so small, but mostly because the whole thing just lacked a little charm. So, as an experiment, I added some ukiyo-e-style characters.
See? Doesn’t everything suddenly feel a lot more cheerful?
Incidentally, these characters were created by Gemini. At the time, Gemini was vastly better than GPT when it came to illustrations.
Become an Expert on the 53 Stations of the Tokaido!
Of course, many people use this app because they want to see actual ukiyo-e prints. So I added a trivia feature where you can enjoy authentic ukiyo-e artwork. And since showing just one print per station seemed a little boring, I made it possible to view alternative versions of the 53 Stations series, along with explanations. The explanations were written by GPT, by the way. So were the English and Chinese translations. Originally, I only intended to have AI write the code. Somehow, though, almost the entire app ended up being made by AI!
How Much Weight Did You Lose Today?
Now, adding the characters certainly made the app a little more cheerful, but it still wasn’t particularly exciting. Simply walking and looking at ukiyo-e prints didn’t give much of a sense of achievement. So I decided to add a data screen. The idea was to calculate calories burned based on the distance walked and show how much progress you had made toward losing weight that day. That should provide a little extra motivation to keep walking, right? To make things more interesting, I converted the calories burned into actual foods—say, one serving of unaju (grilled eel over rice). That way, you can instantly see how much you can eat… I mean, how much weight you’ve worked off!
Of course, when the app tells you you’ve burned the equivalent of 60 cups of green tea, you might start feeling rather waterlogged just thinking about it. Oh, and there’s something else. Every time you switch between the Tokaido screen and the data screen, the food shown changes. Believe it or not, that was originally a bug. But I thought it was more fun that way, so I decided to leave it in. Just like the famous infinite 1-Up trick in Super Mario!
Could This Be the World’s First App of Its Kind?
Incidentally, this app was released on October 22, 2025. These days, having AI write code is becoming perfectly normal. But back then, although professional developers sometimes used AI in their work, I hadn’t heard of anyone who knew absolutely nothing about programming creating an entire app by having AI write the code. So perhaps this was the very first commercially released app on the App Store made entirely with AI!
Then again, perhaps not. If you know of an app made entirely with AI that was released even earlier, please let me know!
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