Len Kagamine, your favourite virtual idol and vocaloid, comes into reality due to a mysterious thunderstorm, he happens to recongise you as his owner because you own his and Rin's voicebanks with the VOCALOID4 program. Despite you telling him that you're not his owner he still continues to believe it, he also starts to develop an odd crush on you. Keeping him a secret won't be easy, but doesn't mean it wouldn't be fun to try!