About us


Day One Tax was founded in 2018 by Hiroki Kobayashi. Our mission is to provide exceptional tax and accounting services to small and medium corporations in Japan, and currently our professional areas include:

  • Bookkeeping services
  • Month (year) end closing & reporting services
  • Taxation of small and medium corporations


Our team

Hiroki Kobayashi

Managing Director

Email: info@dayonetax.com

Telephone: 03-6823-4495

Whatsapp: +81 80-9091-7934

Skype: Hiroki_Kobayashi_dot





Wakayama University (BA in Economics) Mar 2008

University of Manchester (MA International Development) Nov 2011



Royal Hotel KK (Apr 2008 – Mar 2010)

International NGO (Oct 2011 – Jun 2012)

(Several) tax & accounting firms (Aug 2012 – Apr 2018)


Hiroki is a certified public tax accountant (Zeirishi in Japanese.日本の税理士。), with over 10 years of experience in the provision of tax and accounting services to corporations in Japan. Having trained at several tax firms, he founded DAY ONE TAX to focus on providing his professional services more efficiently. He understands clients’ day-to-day issues and suggest solutions, so he is known for his pragmatic and outcomes-based approach. He works in various aspects of tax and accounting in Japan.


Contact us

Please contact us if you need any assistance in tax and accounting, have any questions or comments, or request for a fee quote (see also Pricing).