In 2000, after learning of Daniel Cross' betrayal of the Brotherhood, Hajime implored the camp's overseer Yuri to evacuate the camp and regroup with the Assassins in Osaka. Before the discussion was over, the Templar agent Maxime Gorm and his team had already discovered the camp based on Cross' intel and started eliminating the Assassins. Yuri was struck by several bullets and implored Hajime to take her young son, Tomo Sakagawa, to safety. The two fled into the mountains and escaped Epsilon Team, eventually moving to Tokyo.
On 28 July 2017, Hajime was contacted by the now-adult Tomo, informing him that he had tracked Gorm to a clinic in Switzerland run by a Dr. Nathalie Chapman. Hajime invited Tomo to his shop in the Akihabara district the next morning, where they discussed Maxime and Nathalie. During their meeting, Tomo formulated a plan to infiltrate the clinic.
- Hajime (はじめ) is the Japanese word meaning "beginning" (初め / 始め). Shimada (島田 / 嶋田) is a Japanese surname meaning "island rice field".