StudyX Japanese Letters Table Developer Interview: A Kana Chart Built at Home for a Four-Year-Old

The first commit of StudyX Japanese Letters Table is dated September 2, 2022, and version 1.0 reached the App Store on September 20. It is a one-screen app written in SwiftUI, one of the older StudyX apps. In July 2025 its audio was replaced, and in March 2026 it gained uppercase and lowercase romaji modes and a listening game called ききとりあそび.

Why a kana chart, and how did it end up in its current form? I asked hiroki, who made it. The answers are kept as close to the original Japanese as translation allows.

A daughter learning letters and sounds

Q. The first commit is September 2, 2022. Why a kana chart?

My daughter was four at the time, right at the age of connecting hiragana and katakana to their sounds. So I made it, DIY style. She used it to check the sounds of her own name and played with it.

Q. From first commit to release took about 18 days.

I was used to building apps in SwiftUI, so I could make it and release it quickly. I always try to build small and ship, and this app is especially simple, so it took shape fast. AI was no help at all back then, so I wrote every line myself.

Q. There are paper charts, bath posters and free apps everywhere. Why make your own?

I made it for my daughter to use. Being able to play sound is a big strength of an app. The free apps were low quality, and many showed ads even though they were for children. There was nothing I could use, and I don’t think things have changed much.

What I care about is simplicity. A child should be able to use it without getting lost, safely. That matters most to me. Not many things are made with that in mind, so I think the people who use it share that view.

As a maker

Q. Most StudyX apps today are Flutter, but this one is Swift.

I started out building iOS apps in Swift for work, and later moved to Flutter so I could support Android too. Now I sometimes write native code and sometimes use Flutter. To optimise things like drawing performance you need native code, so it depends on the app.

Q. What was hardest about building something every Japanese person already knows?

The kind of thing I wanted, simple, beautiful and easy to use, is rare among children’s apps. So I only thought about giving shape to what I wanted. The difficulty I always feel when building apps is how to realise my ideal technically. I don’t think much about anything else.

Q. How did you learn hiragana yourself?

From around age four I was hooked on a game of copying whatever caught my eye into a notebook. I remember learning hiragana that way, along with kanji, numbers and anything else I saw. So Japanese class in elementary school was ground I had already covered, and I was bored stiff.

Honestly, though, that had no particular influence on this app. It was built entirely around my daughter’s needs.

Layout, switching and the writing space

Q. The chart starts with the あ column on the right and runs left to わ.

Japanese is a language written vertically, so I followed that.

Q. Dakuten, handakuten and yōon swap the whole chart with a button. Why not one big chart?

I wanted it to work on iPhone as well as iPad. Screen size led to the current design.

Q. The writing space is on iPad only.

That is also screen size. There wasn’t enough room on iPhone.

Q. There is one black pen, no colours or sizes, and erasing clears everything.

More choices let you try more things, but they also make a tool harder to use. The main purpose of this app is linking letters to sounds, and writing is a bonus. So I kept it simple. If you want to write properly, write on paper. I designed it with that trade-off in mind.

Romaji

Q. The romaji is Hepburn, except を is shown as “wo”.

I matched the way you type it on a keyboard.

Q. There are two modes, uppercase “A” and lowercase “a”.

Unlike hiragana and katakana, romaji has capital and small letters. I hoped this would be a natural chance to notice that.

The differences between Hepburn and Kunrei, and the 2025 revision of the official spelling rules, are covered in Hepburn vs Kunrei romaji.

The listening game

Q. ききとりあそび plays a word one kana at a time rather than as a whole word. Was that deliberate?

Yes.

Q. A wrong tap sends you back to the first letter. Did you worry that was too strict?

That is an adult’s way of thinking. Children enjoy correcting themselves again and again. It is something I learned from Montessori education.

Q. When the next letter is a dakuten or yōon kana, the chart switches automatically, which is also a hint. Where do you draw the line on helping?

I always want to design the experience so the child can discover something on their own.

Q. Words with a small っ or a long ー are never asked.

Because you can’t answer them from the chart. Parents and others can fill that gap by talking with the child. I think apps and people should complement each other: people do what apps can’t, and apps do what people can’t.

Having nothing

Q. There are no scores, no rewards and no progress records.

Children find joy in trial and error itself, so I don’t think outside rewards are needed. Very few children’s apps care about that. I design things for children based on the ideas of Montessori education.

Q. Of seeing, hearing and writing, which matters most?

They all matter equally. More than any one of them, the relationships between them are what’s essential, and what matters is that those relationships grow rich.

Q. A four-year-old and an adult learning Japanese abroad. Is it a stretch to give them the same chart?

No. A tool that is simple, beautiful and easy to use is, by its nature, for everyone.

Two years and ten months of silence

Q. From September 2022 to July 2025 the app wasn’t touched for about two years and ten months.

It was already complete as far as features went, so there was nothing to add. Then my younger daughter started using it, and I noticed various things. I also thought a game-like mode would be fun, so I built that idea. That became ききとりあそび.

Q. Is there anything in the 2022 version you would redo?

No. Reality is always the best version.

Users, and what comes next

Q. It is downloaded outside Japan too. Who do you think uses it?

Probably Japanese families living abroad, using it for their children.

Q. The app’s text is Japanese only. Will you translate it?

I think it is better left in Japanese.

Q. How big do you want the app to become?

It is something I made DIY, so it doesn’t need to get bigger. If the people who want an app like this use it, that’s enough.

Q. What does it mean to you to make the first tool a child learns letters with?

I don’t think about it in particular. I just always want to make things that are comfortable for the person using them, child or adult. If someone learned their letters with this app, I would be honoured to have helped.

About the app

Tap a letter to hear it, and switch between dakuten, handakuten, yōon, katakana and upper or lowercase romaji. On iPad there is a writing space beside the chart, and in ききとりあそび you tap the letters of a word as it plays. It is a paid app with no ads and no in-app purchases.

For a first session, see Getting Started with StudyX Japanese Letters Table, and for everyday use, everyday ideas for the app. The app itself is described on the StudyX Japanese Letters Table page.