Ten years ago, Soichi was said to be a kind and caring person, as shown when he reads to his young daughter Misora Isurugi, remembering all the things she liked. According to Sawa's investigation of him, Soichi was also described to be someone who was friendly and had a strong sense of justice. However when he returned to Earth with Pandora's Box, he was possessed by Evolto. During his possession, Soichi was constantly struggling for control of his own body, although his attempts were in vain.

