Masaya Kumagai

Researcher at SAKURA Internet Research Institute, Kyoto University, and RIKEN AIP. Creator of Starrydata — an inorganic materials database. I love turning ideas into prototypes.

Joined on Apr 22, 2026

Masaya Kumagai

Nov 13

The AI wrote a page from my notes, and I can't tell which note a sentence came from

#showdev #llm #rag #opensource

3 min read

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Masaya Kumagai

Nov 12

The note keeps the final number, but not how it was calculated

#showdev #science #research #opensource

2 min read

Masaya Kumagai

Nov 10

The log you keep every day becomes a graph right inside the note

#showdev #datascience #dataviz #science

2 min read

Masaya Kumagai

Nov 9

Keep the sentence you just read on a web page, without leaving the page (This week in Graphium, Nov 2 - 8)

#showdev #opensource #research #llm

3 min read

Masaya Kumagai

Nov 7

Compare the methods of the papers you read, and decide what to try next

#showdev #science #llm #research

2 min read

Masaya Kumagai

Nov 6

The detailed conditions I knew on the day I measured were gone when I looked at the graph later

#showdev #opensource #productivity #ai

3 min read

Masaya Kumagai

Nov 5

The notes you stopped reading can still answer you

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Nov 5

The Word files and PDFs I never reopened were still sitting in a folder

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Nov 5

Hand a plan and all its step notes to a person or an AI as one file

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Nov 2

What Graphium can do 05: Use something made in another note as an input to this step

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Nov 2

This week in Graphium (Oct 26 - Nov 1, 2026)

#showdev #opensource #productivity #ai

3 min read

Masaya Kumagai

Oct 29

What Graphium can do 04: Start without an account, and your notes stay in your own folder as plain files

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Oct 29

What Graphium can do 03: Calculate between cells of a table

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Oct 28

What Graphium can do 02: Wrap one piece of work in a step, and the order of your procedure becomes a diagram

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Oct 26

What Graphium can do 01: Mark what you wrote as input or output, and a diagram of the steps builds itself

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

Oct 26

This week in Graphium (Oct 20-26, 2026)

#showdev #opensource #productivity #ai

2 min read

Masaya Kumagai

May 5

Write notes the way you always do — structure comes out afterwards

#ai #productivity #science #architecture

5 min read

Masaya Kumagai

May 4

Why we built provenance into a notes app

#documentation #product #productivity #science

4 min read

Masaya Kumagai

Apr 23

I Want to Build a Note App Where Discoveries Happen

#showdev #opensource #productivity #sideprojects

5 min read

DEV Community

Masaya Kumagai

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Writing Debut

The AI wrote a page from my notes, and I can't tell which note a sentence came from

Want to connect with Masaya Kumagai?

The note keeps the final number, but not how it was calculated

The log you keep every day becomes a graph right inside the note

Keep the sentence you just read on a web page, without leaving the page (This week in Graphium, Nov 2 - 8)

Compare the methods of the papers you read, and decide what to try next

The detailed conditions I knew on the day I measured were gone when I looked at the graph later

The notes you stopped reading can still answer you

The Word files and PDFs I never reopened were still sitting in a folder

Hand a plan and all its step notes to a person or an AI as one file

What Graphium can do 05: Use something made in another note as an input to this step

This week in Graphium (Oct 26 - Nov 1, 2026)

What Graphium can do 04: Start without an account, and your notes stay in your own folder as plain files

What Graphium can do 03: Calculate between cells of a table

What Graphium can do 02: Wrap one piece of work in a step, and the order of your procedure becomes a diagram

What Graphium can do 01: Mark what you wrote as input or output, and a diagram of the steps builds itself

This week in Graphium (Oct 20-26, 2026)

Write notes the way you always do — structure comes out afterwards

Why we built provenance into a notes app

I Want to Build a Note App Where Discoveries Happen