Numbers to AI.
People beside every decision.
DORONCO Accounting Firm
01 — Data
Numbers, to AI.
Bookkeeping, journal entries, voucher checks, reporting. AI agents take on the routine work and make your business numbers visible in real time.
02 — Agents
From meeting notes to the next move.
Built on tl;dv meeting notes, our agents coordinate with one another to get ahead on the action items and next steps that come out of every meeting.
03 — People
People, beside every decision.
Key judgments and final approval rest with CPAs and tax accountants. AI and people work together to support your business decisions.
AI agents are fully up and running. Final judgment stays with qualified professionals.
About
An accounting firm delivering AX/DX solutions beyond tax.
Beyond tax advisory, year-end closing and management support, we build AI agents and offer DX consulting, web design, marketing support, and interpretation and translation. Teams with different specialties back both the numbers and the decisions behind your business.
accounting software go live
Chinese, Vietnamese and Filipino
serving all of Japan and overseas
experience at a major audit firm
Partners
Cloud accounting and AI tool partners
Strengths
AI removes the busywork. Our team safeguards quality.
AI that clears your busyworkAI agents designed and built for your business
Since May 2026, our AI agents integrated with cloud accounting software have been in full operation. Everyone on the team uses AI every day, for everything from email and research to ordering office supplies. Because our advice comes from real practice, our implementation proposals stay realistic.
Quality built into the organizationJudgment and accountability rest with qualified professionals
Our representative brought the quality-control methods honed at Deloitte Touche Tohmatsu into the way we run the firm. Staff handle the day-to-day work and a CPA and tax accountant performs the final review. This two-tier check means we never depend on any single person.
Wherever you are, whatever your sizeFully remote service across Japan and overseas
Our entire team works together online, so we respond quickly to regional companies and businesses expanding overseas. From sole proprietors to corporations, we propose a plan sized to your workload. A free consultation shows where you can gain efficiency.
Service list
Our services
TaxTax · Filing · Advisory
Tax audit representation
We prepare financial statements built to withstand tax audits, and our representative or your assigned accountant attends the audit. We deal with the authorities on your behalf and firmly assert your position when views differ.
Tax planning, advisory and business consulting
Regular profit-forecast simulations, tax-saving proposals and estimates of upcoming tax payments help you make decisions ahead of time.
Corporate closing and tax return filing
The methods you choose change the tax you pay, so we propose the closing that works best for you. Whether it’s your first filing, your books aren’t done or a deadline has passed, talk to us.
AccountingBookkeeping · Cash flow · Payroll
Bookkeeping and in-house bookkeeping advice
We take care of bookkeeping and financial statements, and also help if you want to keep your own books in the cloud accounting software you already use.
Cash-flow support
From cash-flow statements and forecasts to explaining your finances to banks and joining loan meetings, we draw on our representative’s experience auditing financial institutions.
Payroll and year-end tax adjustment
We handle payroll, year-end tax adjustments and statutory reports. Ask us about drafting work rules and hiring support, too.
AIAI Agents
AI agents for accounting
Incoming and outgoing payments, journal entries, voucher checks and more. We design what to entrust to AI and where people should check.
AI agents for HR
Onboarding and offboarding, changes to dependents or commuting routes, pay raises and more. We design everything down to personal-data handling and review flows.
AI agents for general affairs and legal
Buying supplies, reviewing contracts, handling paperwork through to signing and more. We build in approval flows and risk controls.
DXDX · Web · Marketing
DX consulting
From rethinking workflows and selecting and implementing tools to launching new businesses, we support DX across your operations and back office.
Web design
We handle landing pages and websites end to end, from planning, design and development to post-launch optimization (LPO).
Marketing support
We work alongside you from marketing strategy and media planning to running and continuously improving your ad campaigns.
LanguageInterpretation · Translation
Interpretation
Interpretation between Japanese and English, Chinese, Vietnamese or Filipino for meetings, negotiations and interviews.
Translation
Translation of contracts, financial statements, internal documents and more between Japanese and English, Chinese, Vietnamese or Filipino.
Fees are proposed based on workload. Start with a free consultation, and we’ll assess where your business can gain efficiency.
Our AI Agents
A multi-agent system built for accounting firms.
With tl;dv meeting notes at the core, we built our own AI agents in-house, shaped around how an accounting firm is organized and how it works. The agents coordinate with one another to support the work of the principal, each team member and every client.
the principal & tax accountants
team members
each client’s work
Every conversation,
connected.
We record every meeting and share it across the whole team and our AI agents. You never have to explain the same thing twice, and even if your contact changes, we pick up with the full history in hand.
Tax savings, lower costs,
and even more revenue.
Our AI agents independently research your numbers and the latest tax rules and programs, and our CPAs and tax accountants make the final call before advising you. Beyond cutting costs through tax savings and efficiency, we help grow your sales by connecting you with the right people and companies.
“You already took
care of that?!”
We move ahead on the next actions from your meetings, and on the preparation that comes next, without waiting to be asked.
Tajima was product lead for “satto workspace”, SoftBank’s enterprise AI agent, before joining DORONCO to lead AI agent development for the firm and its clients.
Talk to us about AI agent developmentVISION
In-house→Accounting & tax firms→Professional services→GlobalWe will take the AI agents refined in our own practice to accounting and tax firms, then to professional services as a whole, and on to the world.
Quality & AI Policy
AI does the work. People make the call.
AI agents handle routine work; qualified professionals make the key judgments and give final approval. Human-in-the-Loop (HITL) is the foundation of everything we do.
- Client data is handled only in services configured so that inputs are not used for model training
- AI output is verified against current laws and standards and the expertise of qualified professionals
- We disclose our use of generative AI to clients
AI agents
Routine work such as journal entries, voucher checks and document preparation
Accounting staff
Experienced staff review the work
CPAs & tax accountants
Key judgments, final review and approval
Works
From IPO preparation to hands-on AI adoption.
Selected engagements since 2021, from internal controls at listed companies and spot CFO work for growth companies to AI agent rollouts.
01 — IPO
IPO application documents
TSE Growth-listed
02 — J-SOX
J-SOX implementation
TSE Growth-listed
03 — Review
Reporting package review for overseas subsidiaries
TSE Prime-listed
04 — Spot CFO
Spot CFO for growth companies
Startups and growth companies
05 — AI Agent
AI agent implementation
Manufacturing, construction, cross-border e-commerce
06 — Due Diligence
Financial due diligence and PMI
M&A
07 — Closing
Faster closing and budget planning
Operating company
Message
- About 10 years at Deloitte Touche Tohmatsu LLC, working on financial audits (including IT audits) and IPO support
- As head of finance, accounting and IR at a listed company, reporting directly to the CEO, drove efforts to raise corporate value
- Led business planning and fundraising (¥1.3 billion in debt and equity) from strategy through execution
- Now heads the firm, leading a wide range of work beyond tax and accounting, including AI agent development and marketing support
- Lecturer (current), Special Course for Tax Accountants, School of Economics, Aoyama Gakuin University
In the end, the one who takes responsibility and decides must be a person.
We have put AI at the core of our practice, and since May 2026 our AI agents have been in full operation in our tax work. Even so, we believe final responsibility and judgment must rest with people. Our new brand, DORONCO, reflects our conviction that in the age of AI, human decisiveness and creativity matter more than ever. From tax and accounting to AI adoption and broader business challenges, please feel free to reach out.
Team
Professionals across disciplines, working as one team.
Tax and management support, AI agent development, web design and marketing: our specialist teams work together to take on your challenges.
Careers
Representative · CPA · CPTA
Yasuyoshi Arai
Representative / CPA & CPTA
Head of AI
Kazuki Tajima
Head of AI
AI Tech Lead
Fifi Lo
AI Tech Lead / International business advisor & interpreter
Business Support Advisor
Yukiko Omori
Business support advisor
Marketing & DX Advisor
Yuji Sunagare
Marketing & DX advisor
Web Designer / Digital Ads
Anju Hosoi
Web designer & advertising advisor
Engineer / Digital Ads
Yukiho Ochi
Engineer & advertising advisor
Intl. Corporate Advisor
Nguyen Thi Nga
International business advisor & interpreter
Intl. Corporate Advisor
Ayumi Saito
International business advisor & interpreter
+ 5 other CPA / Tax Accountants & Staff
Development partners in India
AI Development Specialist
Himanshu Rathore
AI development specialist
AI Development Specialist
Param Shelar
AI development specialist
News
News
Speaking at tl;dv User Meetup 2026 Autumn
Kazuki Tajima, our Head of AI, will present “An accounting firm building its own AI agents?!”, with a live demo of how we built tl;dv into our in-house AI.
Venue: Kioi Conference, Tokyo Garden Terrace Kioicho | Free to attend
This event has ended.
Quinnos General Accounting Office becomes DORONCO Accounting Firm
We are rebranding under our new name, DORONCO. Our former website will remain available for a while.
View former siteTwo offices: Tokyo and Nagoya
Our Tokyo office is in Higashi, Shibuya-ku (8 min walk from Ebisu Sta.), and our Nagoya office is in Sakae, Naka-ku (5 min walk from Fushimi Sta.). Our fully remote team also serves clients across Japan and overseas.
View locationsOffice
Firm profile
- Firm name
- DORONCO Accounting Firm
(formerly Quinnos General Accounting Office) - Representative
- Yasuyoshi Arai, CPA & Certified Public Tax Accountant
- Services
- Tax advisory, year-end closing and management support; AI agent development and implementation; DX consulting; web design; marketing support; interpretation and translation
(Group company: Simple Inc.) - Service area
- All of Japan (Hokkaido to Okinawa) and companies expanding overseas
- Tokyo office
- GROVE 202, 2-27-4 Higashi,
Shibuya-ku, Tokyo 150-00118 min walk from Ebisu Sta. / 11 min from Shibuya Sta. / 9 min from Daikanyama Sta.Google Maps ↗ - Nagoya office
- Fushimi FG Building 8F,
1-10-29 Sakae, Naka-ku, Nagoya, Aichi 460-00085 min walk from Fushimi Sta.Google Maps ↗ - Phone
- 0120-627-276 (both offices; toll-free within Japan; 9:00–19:00 JST)
- arai@doronco.ai
- @doronco_accounting
FAQ
Frequently asked questions
Can you advise us remotely even if most of our receipts are on paper?
Yes, and we can also advise you on going paperless. Note that identity verification (KYC) is carried out in person or by mail.
Can we just talk before engaging you?
Yes, we welcome consultations before you engage us. Reach out by phone, LINE, Instagram DM or email.
Can we contact you via LINE or Instagram DM?
Yes. We accept first inquiries and meeting bookings via LINE and Instagram DM. Questions that need a specific tax judgment are answered in a meeting, once we understand your situation.
Who will handle our account?
Depending on the size of the engagement, we form a team of one or more people, led by a CPA. For larger teams, we assign a lead contact.
What communication tools do you use?
We currently use Chatwork, and can also work in Teams or other tools on request.
What does the process look like up to signing?
Four steps: understanding your needs, reviewing your records and internal controls, proposal and quote, and contract.
How do you manage information security?
We have a designated information security officer, continuously update our internal rules, and keep strengthening our technical security.
Contact
Start with a free consultation.
From tax advisory and IPO consulting to AI agent development and adoption. We are happy to talk before you engage us.