About us

Our Team


Co-Founder and CEO
Jim Weisser

Jim is a serial entrepreneur and angel investor, Jim has founded a number of companies and has lived in Japan since 1993.

A graduate of Rice University with a Bachelors in Chemical Engineering, he has founded multiple companies in Japan. Just prior to establishing SignTime in 2020, Jim started PBXL KK, which provided cloud PBX services to Japanese businesses. PBXL KK was acquired by Cisco Systems/BroadSoft, Inc. in 2015. He was also involved in business planning and development activities as Regional Manager of the Cloud Calling Business Unit at Cisco Systems.

Jim was featured in "The Quiet Comeback II", a book on Japanese entrepreneurship and is currently a co-chair of the American Chamber of Commerce in Japan's DX (Digital Transformation) Committee. He is also a judge in the Asian Entrepreneur Awards, a competition established by Tokyo University (Todai).

He is also big fan of Umeboshi!

Jonathan Siegel

Jonathan Siegel is a co-founder of SignTime. Jonathan is a serial entrepreneur who has founded companies in e-commerce, cloud services, and digital signatures and is currently managing partner at Xenon Ventures. He also holds multiple patents related to digital signatures. Jonathan is also a serial learner, having completed an MBA, a law degree, and a helicopter license. His book, ‘The San Francisco Fallacy - The Ten Fallacies That Make Founders Fail’ has been translated into Japanese.

Executive Officer
Yusuke Sakayanagi

At SignTime, Yusuke is responsible for business development, partner relationships, and sales strategy in Japan. In his previous position at NTT DOCOMO Inc., Yusuke was in charge of strategy for the Smart Life Business Division, as well as strategy roles in corporate development and 5G. Prior to NTT DOCOMO, he held business planning roles at NIFTY Corporation (now Fujitsu Cloud Technologies Limited) and was corporate sales manager at Sony Biz Networks, Inc. Yusuke became an executive officer of SignTime K.K. in January 2021.

Yoshimasa Aikawa

Yoshimasa Aikawa is currently an executive advisor to SignTime. At the beginning of career, he joined Fujitsu Kyushu Systems in 1982 as a Systems Engineer, and progressed through the ranks, eventually becoming Executive Director. Subsequently, he became President of Fujitsu Cloud Technologies in April 2017. He has extensive cloud experience both from his time at Fujitsu and while establishing Aitcz. Yoshimasa provides ICT consulting services to a variety of companies. Yoshimasa became an advisor to SignTime in May 2022.

Hirokazu Sampei

Hirokazu was the first president of Docusign Japan and is a highly regarded thought leader in the field of Japanese e-signatures and electronic contracting. He is also a data communications and IP expert, having worked at Cisco designing Internet infrastructure for telecommunications carriers and has extensive experience in Cloud and SaaS platforms, working with Polycom, A10 and DocuSign, among other leading tech firms. In 2019, he founded meUP, Inc. in 2019, which consults on retention and acceleration programs for businesses. He is an avid and experienced rally car enthusiast, and became an advisor to SignTime in March 2021.

Jerry Black

Jerry Black is currently a Senior Advisor to the Group CEO of The Aeon Co., Ltd. group and is responsible for providing leadership on transformation initiatives across the group. In 2009, he was named CSO, CIO and CEO of the company’s ASEAN Division. Other roles included Deputy President of Aeon Retail, CDO, and Senior EVP responsible for merchandising strategy, marketing, supply chain management and information technology. He also has significant experience in business restructuring, financial re-positioning of troubled companies including a strong foundation in financial analysis, capital allocation and business portfolio rationalization as well as a track record in strengthening corporate governance.

Work with SignTime

Web Sales Manager


Engineering Manager


Engineering Manager


What we do

Premium Remote Work
SignTime believes in providing a good work/life balance for our employees.
SignTime encourages remote work - and we believe it's important to have high-quality workforce enablement tools for our team members. We provide all the necessary laptops, displays, and other IT tools to help our team members be successful.
Flexible working hours.
Freedom of time, place and work location.
At SignTime, employees can work anywhere, anytime they want. Our team members live in different countries such as Japan, the U.S., Europe, and Southeast Asia, and we work on projects with time differences in mind. We're not bound by the concept of time and respect a work style that allows our members to work to the best of their ability.
We are a family friendly employer.
Family comes first
At SignTime, we understand what having a family is like. In addition to embracing remote work and hyper flextime, we also consider the working hours and work content that fits the lifestyle of each team member and their family's lives. We understand that some things can wait and some can't!


Company Name SignTime K.K. / サインタイム株式会社(In Japanese)
Type of Business Developing and operating e-signature service SignTime
Location Toranomon Hills Business tower 15F,
1-17-1 Toranomon, Minato-ku, Tokyo 105-6415, Japan

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