Ryoya Kawai

is a web developer loves to hack with curiosity 👍


ryoya.kawai (at) gmail.com


  • JavaScript, Node.js, PHP, Perl, Java, Golang, Python, Kotlin
  • AWS, Azure
  • Docker, Jenkins, CircleCI
  • CodeceptJS (E2E Test)

:: WORKS ::

Pepper sings!

Pepper is the human shaped robot who is able to move, speak, dance and so on enabled by lots of sensors, and is able to be installed custom developed applications to execute activity just like a smart phone.

Goal of this project:

Final goal of this project was to make Pepper to sing a song. However, at the beginning of the project, Pepper was not open to public so much, so the project was highly confidential. Because of that reason, the project member was only a few. And the developer was only myself. I developed the bridge to connect "VOCALODUCER" developed by Yamaha to Pepper, and developed Pepper's gesture/dance as well as pages in his/her tablet on the chest during the entire process until singing.
"VOCALODUCER" is the backend system to compose song with several parameter and lyrics.

Procedure make Pepper to sing:


  1. asks user to input lyrics by using tablet
  2. asks user to select melody and music genre from the list
  3. then, send request to VOCALODUCER to compose music by using parameters from user
  4. receives composed music as a response of VOCALODUCER


The challenges of this projects were following:

Bunch of try and error was experienced during this development, however finally I succeeded both compete to develop within tight schedule. The completion was at the event venue about 1 hour before the beginning, though.

Panel Discussion:

(Released Date: 2014/09/20)

POCKET MIKU (ポケット・ミク)

POCKET MIKU is the first gadget/hardware musical instruments in the world that is able to sing with voice of Miku Hatsune, and the gadget is be able to make sing a song by playing as same way as playing the piano.

My role:

My role in this project was to develop utility application to update lyrics of POCKET MIKU from browser with using Web MIDI API.
At the moment of the project, HTML5 was in early stage, and Web MIDI API was the one of the experimental web browser's API and first API that connect directly to external hardware from web browser. So this utility web application was the first web application in the world targeting for consumer hardware products that controls external hardware with using Web MIDI API.

Movements after shipment:

The most excited thing is that the source code of this utility web application was open to public at GitHub, so using that source code as a reference to develop applications for POCKET MIKU by DIY software developer, such as who loves Maker Faire for example. To develop its applicaiton gradually got be popular, and lots of demo videos for those applications were shared on YouTube.

It was such a remarkable moment for both project members and those who joined this movement.


The challenges of this projects were following:

Link to the product page:

(Shipped Date: 2014/04/03)

:: Community Activity ::

(2014/09/13 at Google Japan)

Web Music Developers JP

Founded this community in Sept. 2013 with awesome 5 co-foundors, @agektmr, @toyoshim, @aike1000, @g200kg, @yukio_tada. The community is grown around 200 members. I am in charge of the organizer of the community.

The word "Web Music", stands for especially mixture of Web Audio API and Web MIDI API, was invention of this community.

Web Music Hackathon:

Most known activity in this community is the "Web Music Hackathon". Here is the reports for each hackathon.

The hackathon is holding worked with incorporated associations and companies listed below.


Meetups with inviting spec editors and others as speaker.


Here is the step by step tutorial, a.k.a Codelabs, for music related API.
This Codelabs was recognized by Google's Open Source Office.

Panel Discussion and Presentations:



HTML5 Experts.jp

As one of HTML5 experts, wrote about 10 articles at html5experts.jp especialy for music related API and Google I/O.

Play Music on Web Browser (Web Audio API, Web MIDI API)

The journal of the Institute of Image Information and Television Engineers. Explaining how to make, to handle and to play music by browser. (Sorry, the journal is not open to public.)


Web MIDI / USB / Bluetooth App

Mountains Lights

Web MIDI Message Viewer [Left]:

Display recieved MIDI messages in real time both USB-MIDI and BLE-MIDI with Web MIDI API and Web Bluetooth API.

交通系カードリーダ [Right]:

Read and display transit history of public transportation touch less card with Web USB API.

Technical articles in blog

Chrome Extension

Test Automation

  • AndroidアプリをBitriseでCIする。 [blog]
  • AndroidアプリをCircleCIでCIする。 [blog]
  • Firebase Test LabでUI Testを実行する。[blog]



Clock face for Fitbit fitness tracker

Unique features:

See here for more information.

blog post

(Shipped Date: 2018/05/27)

Get it on Google Play

Web Music Browser

This Android app is the web browser supports to send/receive OSC (Open Source Control) message.
OSC is the protocol that are transported across the internet and within local subnets using UDP/IP and Ethernet.

Sending packet form web browser against specific client without any negotiations is still not allowed in 2021. However, would not that great if it is allowed and to develop the controller applications with OSC as web application only with web technology, such as HTML/CSS/JavaScript? Well, this app supports that.

So in short, with this Android app, the applications developed on top of web technology such as HTML/CSS/JavaScript having feature to send/receive OSC message is able to run.

Please refer this document for more API specification in detail.

Google Play and the Google Play logo are trademarks of Google LLC.
(Shipped Date: 2016/08/01)