Keep your feelings as colored spheres — a journal with AI
Gently meeting your own story.
What you can put into words goes into a memo.What words can't quite hold becomes a colored sphere, through six questions.
The words and spheres you keep will one day help you know yourself.Patent pending (Japan)
Tone Prism
Then, from the words and spheres you've kept, AI reads the story that continues into your future.The potential sleeping inside you, and your next step, too.
AI Trend Analysis and Letter to the Future are paid-plan features, available during your free first month too.
Some screenshots show the Japanese version of the app. The app itself is available in English.
It's your own life, yet the clues to how you felt don't stay.
Sometimes the "you-ness" you only notice later is left in the scenery of an ordinary day — the kind no photo captures.
Keeping today, together with the Tone Sphere your heart turned to,can become a small cluefor the future you, tracing your own story someday.
Even a day words can't hold can be kept in color.
At the end of the day, answer six questions. A memo can be one word — or nothing at all. Today's feelings become a single colored sphere: your Tone Sphere.
Hold today in a color that belongs only to today.Someday, the scene in that spherewill become a doorway to memory.
One day at a time, "my colors" grow.
What you couldn't see in a single sphere slowly comes into view when you line them up.
"Lately, I've had a lot of spheres like this.""This day was different from usual."
Your time builds up, one colored sphere at a time.
The more you use it, the more Tone Spheres you'll find.
On days you want to write a lot, write a lot.
Leave a passing thought in the morning.Write down a foggy feeling just as it is.One day, jot down an idea that came to you.Little by little, put a plan you've been mulling into words.
"Today's Notes" is a place to freely keep the words of your days.
You can search what you wrote by keyword later.And those words connect to AI Trend Analysis and Letter to the Future,becoming clues for you to trace your own story.
Unexpectedly meet a self you'd forgotten.
A Tone Sphere leaves a bookmark in your memory.
With Tone Prism, your spheres become clues: through "Days with a similar tone" and "The same date," you can trace the feelings your past self left behind.
Meaning that wasn't there when you wrote it can appear as time passes.
The longer you keep going, the more doorways to your past self you'll have.
Your own rhythm, invisible in a single day.
Using several days of spheres and memos as clues,AI Trend Analysis looks back with you.
Small patterns you hadn't noticed can come into view as time builds up.
Tendencies by day of the week. What was happening before your mood shifted.
From what you've left behind, AI looks for small changes and tendencies you haven't noticed yet.
You don't need to write long entries every day.A casual word can turn out to be an important clue later.
AI Trend Analysis is part of the paid plan. During your free first month, you can try it up to 6 times.
No payment details needed.
The words you kept come back from the future.
Among the words and spheres you've gathered, there may be clues to the potential sleeping inside you, and to your next step.
Letter to the Future reads these from your accumulated records,and from a little way ahead,sends words back to you now.
That cycle connects your past self, your present self,and your future self.
Letter to the Future is part of the paid plan. You can receive one every two weeks, including during your free first month.
Keep today. Meet your past self. Notice a self you don't know yet. And then, toward the future.
Tone Prism is not just a diary for recording the present.
Keep today, and return to it after time has passed. Then find what you couldn't see back then.
Over time, the meaning of your records grows.
A journaling service of words, AI, and colored spheres.
In users' words
Feedback from people who have used Tone Prism. Translated from Japanese.
Memo Diary
Looking back through "Days with a similar tone" brings my past self back to me. I really like it.
Memo Diary
I can remember things like, "So I'm in the same state as back then," or "Oh, that happened too." This angle feels fresh.
AI Trend Analysis
I'd only recorded four days in a row, yet I got new insights and even advice on what to do next. It made me realize a casual line I'd written was a key point.
AI Trend Analysis
It pointed out that I'm not at my best on Thursdays. Thinking back, I realized it was true — I'd been going to the gym every day since Saturday, so Thursday was the last and most tiring day. Seeing that, I decided to cut back on my gym days a little.
Letter to the Future
When I write a lot, it offers many different interpretations of me, and that makes me happy.
Letter to the Future
It wrote about exactly the thing I'd been thinking of taking on. I wondered, how did it know?
Tone Sphere
The colors come out so nicely that I can use it as a summary of my day.
These are individual impressions. Results vary from person to person.
One month free, and your choices after that
All paid-plan features, free for your first month.
First month free (1 month)
- Use the same features and limits as the paid plan for one month.
- No payment details needed to start.
- We'll let you know before the free period ends. You won't be charged automatically when your free month ends.
- Afterward, choose the monthly plan or the free plan. If you don't choose, you'll move to the free plan.
- On the free plan, you can keep recording and still read the AI Trend Analyses and Letters to the Future you've received.
Free plan
¥0
- Tone Spheres
- Memo Diary
- Days with a similar tone
- The same date
- Diary export
- Keep recording after your first month
Paid plan
Coming soon
Pricing will be announced at launch
- Everything in the free plan
- AI Trend Analysis: 6 times a month
- Letter to the Future: every two weeks
- Diary export with scores · CSV export
Prices are in Japanese yen (JPY). For details, see: Pricing & Billing (Japanese)
Before you start: frequently asked questions
Do I need to enter payment details to sign up?
No. You can use your free first month without entering any payment details. You won't be charged automatically when the free period ends.
What happens when the free period ends?
We'll let you know before it ends. Choose the monthly plan or the free plan — you only enter payment details if you choose the paid plan. If you don't choose, you'll move to the free plan.
Will my records disappear on the free plan?
No. Tone Spheres, the Memo Diary, "Days with a similar tone," and "The same date" stay available. You can still read the AI Trend Analyses and Letters to the Future you received during the free period. You can export your diary entries anytime to keep them yourself.
What does the AI read? How is my data handled?
AI Trend Analysis and Letter to the Future are generated from the records and memos you've kept. We don't use tracking tools for advertising. For who can see your records, how to delete them, and how AI is used, see our Privacy Policy (Japanese).
Is this a medical service?
No. Tone Prism is for everyday journaling and self-reflection. It is not intended for medical treatment, diagnosis, or therapy.
How often does Letter to the Future arrive?
Once every two weeks. It's fine to have days with just a word. The more you record, the more clues there are to read.
What do I need to use it?
Just a browser on your smartphone or PC. Add it to your home screen, and it opens like an app.
Is the app available in English?
Yes. The app's screens are available in English. AI Trend Analysis is written in English; Letter to the Future is currently available in Japanese only. Some pages — such as pricing and legal documents — are in Japanese only, and the Japanese versions govern.
I'd like to learn more about how to use it
See the How to use page.
To start, just today.
You don't have to write properly every day. It's fine to have days with just a word, or days with nothing at all.
Start by keeping just one day. That day may someday become a doorway to your story.
Why not spend a month exploring Tone Prism?
Start for freeFor your first month, all paid-plan features are free.After that, your Tone Sphere records and Memo Diary stay free.No payment details. No automatic charges.