One-time password authentication can be used by setting up "Authentication by email" or "Authentication by app" by setting up one-time password authentication on the Settings for Identity Verification Methods page.
Detailed instructions are available in the Expo ID Registration Manual on the Ticket Information page on the Expo 2025 Osaka, Kansai, Japan official website.

ExpoID Registration Manual:

https://www.expo2025.or.jp/wp/wp-content/themes/expo2025orjp_2022/assets/pdf/tickets-index/id_registration_manual_en.pdf