Notice of Completion of Share Acquisition (Group Company Formation) by kubell Inc.

atena Inc. (Head Office: Chiyoda-ku, Tokyo; Representative Director: Naoki Shirahige; hereinafter "atena") is pleased to announce that, as communicated in the "Notice of Agreement Regarding Share Acquisition (Group Company Formation) by kubell Inc." dated March 23, 2026, the acquisition of its outstanding shares by kubell Inc. (Head Office: Minato-ku, Tokyo; Representative Director CEO: Masaki Yamamoto; Securities Code: 4448 (TSE Growth); hereinafter "kubell") was completed on April 30, 2026, making atena a group company (wholly-owned subsidiary) of kubell.

There will be no changes to the provision system of our services due to this matter. We will continue to strive to provide services and improve quality so that customers can use them with peace of mind.

For more details regarding this matter, please also refer to the press release "kubell Acquires atena Inc., Operating Cloud Postal Service 'atena,' Making It a Group Company" announced by kubell Inc. on March 23, 2026.

URL: https://www.kubell.com/news/2026/03/kubell-atena.html

■ About kubell Inc.

kubell Inc. (formerly Chatwork Inc.), with the corporate mission of "Making work more fun and creative," operates "Chatwork," Japan's largest business chat service that anyone can easily use and connect with external users. They also broadly develop BPaaS services such as "Takushita," which allows outsourcing various back-office tasks like accounting, labor, and general affairs via chat. From a business chat company, they are transforming into a platform provider that changes "work" with BPaaS. The company name was changed to kubell Inc. (read: Kubell) on July 1, 2024.

Company Name: kubell Inc.
Listed Market: Tokyo Stock Exchange Growth Market
Company Establishment: November 11, 2004 (Founding: July 15, 2000)
Capital: ¥3,008,265,711 *
Representative Director: Masaki Yamamoto
Head Office Location: 1-24-3 Minami-Aoyama, Minato-ku, Tokyo, WeWork Nogizaka
Group Employees: 698 people *
Business Activities: Business chat service, development and operation of related services and new businesses
Corporate Website: https://www.kubell.com/
* As of December 2025