Elastic Arm Illusion (EAI) provides the striking illusory experience of having a longer arm where the virtual arm is visually stretched from the first-person perspective in the head-mounted display (HMD) space. EAI involves one player lying down on their back and another playmate (experimenter) standing on a Wii Balance Board that monitors the weight of the playmate. When the player and playmate grasp one pole and are face to face, the more strongly the playmate pulls up on the pole (assisted by the player) the more weight is moved from the player to the playmate, resulting in the increase of the weight of the playmate. EAI correlates this increment of the weight with the illusory stretch ratio of the arm in HMD space. Thus, the sense of arms being pulled up is transformed into a sense of having a longer arm through the measurement of the playmate’s weight, realizing an ultimate stress-free illusion induction system for the player.