NTT is researching digital twin technology that reproduces not only the outer states, such as appearance, voice, and movement, but also the inner states, such as values and thoughts, of humans. To actualize a future in which human digital twin technology contributes to the well-being of people and society, it is necessary to examine the ideal path of technology evolution from a broad interdisciplinary perspective. This article introduces research activities to pursue well-being as the Grand Challenges of Digital Twin Computing, i.e., Another Me and Mind-to-Mind Communication. © 2022 Nippon Telegraph and Telephone Corp.. All rights reserved.