Maeno Aki exhibits a lively personality, equal parts excitable and irritable by circumstances. His altruistic habits cause his emotions to be easily swayed by others, bearing concern and self-sacrificing actions that extend even to those that've caused harm to him. Upon regaining his memories, Maeno is shown to harbor heavy feelings of guilt as the one who caused Ushirono Natsu's death and Tsugino Haru's ZENO condition. Additionally, being a former ZENO patient himself.