How I Digitally Transformed a BJJ Dojo for 120K Yen per Month

Prologue: The Analog Nightmare

In 2019, I was training at a BJJ dojo in Setagaya, Tokyo.

The training was great. The teammates were great. The instructor was great.

But the operations were chaos.

The Analog Nightmare in Practice

  1. Member roster: An Excel file (on the instructor's PC, no backups)
  2. Attendance: Handwritten paper notebook
  3. Tuition: Cash only, handwritten receipts
  4. Schedule: Handwritten on a whiteboard
  5. Communication: Multiple LINE groups (total chaos)

One day, the instructor said:

"I've lost track of who paid tuition this month."

...Completely unacceptable.

Chapter 1: Defining the Problems

The Instructor's Pain Points

  • Time-consuming: 1-2 hours of administrative work every day
  • Error-prone: Handwriting is illegible, data entry mistakes everywhere
  • Financial chaos: No way to tell who has paid
  • Missed messages: Multiple LINE groups causing confusion

The Members' Pain Points

  • Schedule unknown: Had to check the whiteboard in person
  • Paying tuition is a hassle: Bringing cash every time
  • No idea who's coming: Can't tell in advance who your training partners will be
  • Belt progress unclear: How many more sessions until the next stripe?

My Thought

"Couldn't an app solve all of this?"

Chapter 2: Building the MVP

Initial Design (November 2019)

Minimum required features:

  1. Member registration and login
  2. Schedule display
  3. Attendance tracking
  4. Tuition management (tracking who has paid)

Tech stack:

  • Frontend: Flutter (iOS + Android)
  • Backend: Firebase (Authentication, Firestore, Cloud Functions)
  • Language: Dart

I chose Flutter because one codebase covers both iOS and Android.

Development Period: 3 Weeks

  • Week 1: Design and UI creation
  • Week 2: Firebase integration
  • Week 3: Testing and debugging

Every evening, 2-3 hours of development after training.

First Release (December 2019)

I showed it to the dojo instructor.

"Oh, this is great!"

We started a test run with 20 members.

Chapter 3: Feedback and Iteration

Requests from Members (First Month)

  1. Profile photos: Can't tell who is who
  2. Belt progress: How many sessions until the next stripe?
  3. Training log: Want to know how many times I've trained
  4. Sparring partner selection: I want to train with this person
  5. Notifications: Notify me of schedule changes

Requests from the Instructor

  1. Automatic tuition reminders: Notify members with unpaid tuition
  2. Reporting: Monthly attendance rates and revenue
  3. QR code attendance: Just scan your phone to check in
  4. Belt management: Record stripes and promotions

v2.0 Release (February 2020)

All of the above features implemented.

Development time: 2 hours per night x 30 days = approximately 60 hours

Chapter 4: Inquiries from Other Dojos

Word of Mouth Spreads

A member posted on social media:

"Our dojo uses an app for attendance. It's incredibly convenient."

Other dojos started reaching out:

"We want to use it too!"

Multi-Dojo Support Development (May-August 2020)

Challenge: Every dojo runs differently

  • Dojo A: Monthly tuition model
  • Dojo B: Ticket model (10-session packs)
  • Dojo C: Drop-in (pay per visit)

We built a flexible billing system to accommodate all of them.

The Decision to Go SaaS

"Giving it away for free isn't sustainable."

  • Server costs: 30,000 yen/month (Firebase)
  • Support work: 10 hours/week

We decided to offer it as a monthly subscription SaaS.

Pricing:

  • Basic: 12,000 yen/month (up to 100 members)
  • Pro: 24,000 yen/month (up to 300 members)
  • Enterprise: 48,000 yen/month (unlimited members)

Chapter 5: The Birth of "jitsuflow"

The Name

  • jitsu: Jiu-Jitsu
  • flow: Smooth operations

jitsuflow.app

Domain registration: $12/year (cheap!)

Logo Design

Outsourced on Fiverr: $50

A simple wave design in BJJ's signature colors (blue and black).

Chapter 6: Growth Hacking

Early User Acquisition (September-December 2020)

  1. Reddit post: Posted on r/bjj -- 150 upvotes
  2. Facebook ads: Targeted BJJ-related groups -- spent $500
  3. YouTube sponsors: Provided free accounts to BJJ instructors -- review videos

Results:

  • Registered dojos: 32
  • Members: 890
  • MRR: 380,000 yen

The Power of Word of Mouth (2021)

"jitsuflow is seriously convenient" spread through the BJJ community.

  • Registered dojos: 120
  • Members: 3,200
  • MRR: 1.44 million yen

Chapter 7: Current Status (February 2026)

Numbers

  • Registered dojos: 85 (peaked at 120, declined during COVID, recovering)
  • Members: 1,300
  • MRR: 1.02 million yen
  • Monthly active users: 980

Key Features (2026 Edition)

  1. Schedule management: Class booking and cancellation
  2. Attendance tracking: QR code and NFC tap support
  3. Tuition management: Stripe integration, automatic billing
  4. Belt management: Stripe and promotion records
  5. Training log: Personal dashboard
  6. Video library: Save and share technique videos
  7. Tournament management: Create competition brackets
  8. Community: In-dojo social network

Tech Stack (2026 Edition)

  • Frontend: Flutter 3.x
  • Backend: Firebase + Supabase (partial migration underway)
  • Payments: Stripe
  • Video: Cloudflare Stream
  • Notifications: Firebase Cloud Messaging
  • Analytics: Mixpanel

Chapter 8: Cost Structure and ROI

Monthly Costs (February 2026)

ItemAmount
Firebase32,000 yen
Supabase25,000 yen
Stripe fees36,000 yen (3.5% of MRR)
Cloudflare Stream18,000 yen
Domain / SSL1,000 yen
Mixpanel12,000 yen
Total124,000 yen

Revenue

PlanDojosUnit PriceSubtotal
Basic4512,000 yen540,000 yen
Pro3224,000 yen768,000 yen
Enterprise848,000 yen384,000 yen
Total85-1,692,000 yen

(Note: Actual MRR is 1.02 million yen. The above is list price, before discounts and free trial periods.)

Profit

  • MRR: 1.02 million yen
  • Costs: 124,000 yen
  • Gross profit: 896,000 yen

(Development time not included. I run everything solo.)

Chapter 9: Failures and Lessons

Failure 1: Feature Creep (2021)

Added "this and that" -- UI became overly complex -- churn rate increased.

Lesson: Simple wins. Remove unused features.

Failure 2: Manual Support Was Unsustainable (2022)

Spending 20 hours a week on support inquiries -- nearly burned out.

Lesson: Introduced FAQ and a chatbot -- reduced to 5 hours/week.

Failure 3: Pricing Was Too Low (Early Days)

Basic at 5,000 yen/month -- too cheap to cover support costs.

Lesson: Raised prices in 2021 (5,000 yen to 12,000 yen) -- churn rate barely changed.

Chapter 10: User Testimonials

Dojo Owner A (40s, Tokyo)

"Thanks to jitsuflow, my administrative work dropped from 10 hours to 2 hours a week. I can now focus on training and teaching."

Member B (30s, Osaka)

"Since I can check the schedule on the app, it's easy to drop in after work. Being able to see my belt progress keeps me motivated."

Dojo Owner C (50s, Fukuoka)

"When membership dropped during COVID, the online class booking feature was a lifesaver. The Zoom integration made it easy to run online sessions."

Chapter 11: What's Next

Roadmap (2026)

  1. AI features:

    • Attendance prediction ("How many people will come tomorrow?")
    • Belt promotion timing prediction
    • Personalized training menu suggestions

  2. Global expansion:

    • English and Portuguese support (targeting the Brazilian market)
    • Multi-currency payment support

  3. Expanding to other martial arts:

    • Judo, karate, Muay Thai, etc.

Long-Term Vision

"Connect every dojo in the world through jitsuflow."

There are currently around 100,000 BJJ dojos worldwide.

12,000 yen/month x 100,000 dojos = 1.2 billion yen/month

...Dream big.

Summary: DX Isn't Just for Big Companies

jitsuflow took a dojo that relied on nothing but paper notebooks and fully digitized it for 120,000 yen per month in operating costs.

Benefits of DX

  1. Time savings: Administrative work reduced from 10 hours/week to 2 hours
  2. Revenue growth: Reduced unpaid tuition, increased new memberships
  3. Member satisfaction: Visibility into schedules and progress

All You Need Is the Decision

  • Programming experience? Not required (you can outsource)
  • Budget? Starting at 120,000 yen/month
  • Time? 3 months initially, then 5 hours/month

Start small. Listen to feedback. Iterate.

That's all it takes to escape the analog nightmare.

Links

  • jitsuflow official: https://jitsuflow.app
  • GitHub: https://github.com/yukihamada/jitsuflow
  • Contact: info@jitsuflow.app

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Tags: BJJ SaaS DX Flutter Firebase Startup Dojo Management