This special issue was planned in conjunction with the 25th Interaction 2021 Symposium (General chair: Shinji Mizuno, Program Chair: Sozo Inoue) held online from December 10th to 12th, 2021. The symposium has been held annually since 1997 and has been providing a forum where researchers and practitioners gathered together to exchange and discuss the latest technologies and information related to "interaction." Major topics include computer science such as user interface, CSCW, visualization,

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... ut/output devices, virtual/augmented reality, ubiquitous computing, software engineering, cognitive science, social science, media theory, and art. This symposium has been organized by five Special Interest Groups: Human Computer Interaction (HCI), Groupware and Network services (GN), UBIquitous computing systems (UBI), Entertainment Computing (EC), and Digital Contents Creation (DCC). Three days program of the Interaction 2021 Symposium consisted of a keynote speech, oral presentations, interactive presentations with demonstrations or posters. We had 15 oral presentations (including 5 invited presentations from a previous special issue), 122 interactive presentations (demonstration) and 58 interactive presentations (posters). Since research on "interactions" is progressing rapidly and development is remarkable, it is important to provide opportunities for rapid publications. Therefore, we organized a special issue in conjunction with the Interaction 2021 Symposium to collect papers published in and related research widely at the symposium for prompt publication as journal articles. This special issue started in Vol. 39, No. 5 (1998), which was planned in conjunction with the 1st interaction symposium (Interaction 1997), and this will be the 21st edition of this special issue. We organized the editors for this special issue by inviting 19 chief program committee members from the Interaction 2021 Symposium, and we tried to assign the same editor who took part as the meta-reviewer in the symposium to this special issue. As a result, 31 papers were submitted to this special issue, and 13 papers were accepted (Acceptance rate: 42%). We observed that not only the papers which were submitted to the Interaction 2021 Symposium but also papers with a wide variety of topics were covered in the submission which lead this special issue to an open one. I hope that this special issue will be valuable to all readers who