The Parasitic Finger project explores how humans coexist with uncontrollable finger augmentation with an SMA actuator. What would happen if our fingers, which we use freely in daily life, could move in unrealistic ways, independent of our will? The user may try to use their extended fingers in some way, even if they aren't handling them well. They may sense another creature inside and feel an urge to engage with or care for it. The finger actuator unit weighs just 5 grams and is lightweight, making it comfortable to wear on the fingertips. By regulating the heat of the SMA wires, the SMA actuator can bend in four directions. Unlike human finger joints, they move like tentacles, performing actions such as waving and touching objects. Their vibrations indicate their alertness or cuteness.