About Us
Our Mission
With more than thirty years of professional experience, we assist our clients in each and every stage of their continuous growth. We develop efficient and flexible solutions to support them in achieving their business goals. That's our mission.
Quality Services
We provide the international business community both in the U.S.A. and Japan with quality bilingual (Japanese/English) accounting, tax, payroll and advisory services to over 100 domestic and international clients. Our clients range from a number of industries from large worldwide corporations and SEC listed US companies to local import/export retailers.
Company Profile
Harnessing our more than 30 years of combined experience, we established Oshima Saito LLP in January 2001 with the desire to provide our customers with efficient, customized, and goal-oriented service.
With headquarters in New York City, and branch offices in Los Angeles and in Shibuya, Tokyo (opened January 2001 and October 2008, respectively), we are able to serve our clieants globally.
Our staff is made up of highly experienced American Certified Public Accountants and Japanese Certified Public Accountants with expertise in matters of banking, law and audits. We offer expert knowledge and guidance for a range of accounting needs, including corporate finance management, personal investments, and estate, inheritance and gift tax.
We have provided advisory services, and met the accounting and tax needs of a wide range of clients from private enterprises and small businesses, to international corporations. Our target clients do business in both U.S.A. and Japan, and our staff is able to assist clients in both Japanese and English.
The best feature of our firm is that all three of our international offices will work together to optimally serve you. If you are in Tokyo, with a branch in New York, or vice versa, we can facilitate easy communication in real time without the inconvenience of time differences or language barriers.
Koki Saito, Partner and CPA in U.S.A. & Japan

- 1991: Became a Certified Public Accountant in Japan
- 1995: Became a Certified Public Accountant in the state of California
- 1996: Became a Certified Public Accountant in the state of New York
- 2018: Became a Certified Public Accountant in the state of Hawaii
Mitzi Saito, Tax Advisor

MS in Taxation from Fordham Graduate School, BS in International Management from Seton Hill University after graduation, Mitzi joined KPMG, one of “Big 4” accounting firms in New York and took a role of Managing Director in the individual tax group for Japanese clients. Then, she moved to Ernst & Young in New York, where she served as a partner leading Japanese individual tax team. She joined Saito LLP in October 2020. With more than 25 years’ experience in Individual tax field, her expertise includes cross-border individual tax consultation and tax compliance but also payroll consultation, gross-up calculations and social security benefit consultation for Japanese assignees working in the U.S., individuals with U.S. citizenship and green card, the assignees from Japan and business travelers/trainees/students from Japan.
Naomi Wada, Director

- U.S. Certified Public Accountant
- Senior Manager in Tokyo office
- BA in History, Tokyo Woman's Christian University
- 2007: Became a Certified Public Accountant in the state of New Hampshire
Bo Chen, Manager

Manager in New York office
BA in Engineering, Tianjin University; MS in Engineering, The University of Tokyo; MBA, Carnegie Mellon University. Joined Saito LLP in 2017 after working for a major construction equipment manufacturer in Japan. His specialty includes auditing, accounting, tax return preparation, business valuation, and other various accounting/tax advisory services. He is the Manager of Saito LLP (Saikos Group).
Wei yin, Saito Tax Manager

Manager in New York office
BA in Fukuoka Jogakuin University of Fukuoka
Staff of SOS Bookkeeping LLC, Saikos Group (May 2016-Feb 2017)
Saito Tax LLC, Saikos Group (Mar 2017-Present)
Payroll Calculation, Preparation of Corporation tax, Individual Income Tax Return, and other tax related services.
NY Office