English version could be accessed with the following links.
Table of Contents page is located with the link at "JAXA Supercomputer System Annual Report April 2020-March 2021 Contents".
Compiled PDF of All Reports is available here.
Japanese version is available here at this link, JAXA スーパーコンピュータシステム利用成果報告 (2020年4月～2021年3月).
Access to Older/Newer Reports
Annual reports of older/newer year are available at this link, JAXA Supercomputer System Annual Report.