"Kokoro Shinryaku Robot" was first uploaded on September 20, 2012. It was at first originally uploaded on 2011, however that version was removed from Nico Nico Douga and also Hinata Haruhana's YouTube account (the original version can still be heard in YouTube reprints and Hinata Haruhana's album "Mechanical Mystery"). Not too long after the original's upload, Hinata Haruhana also uploaded her own cover to the song with it's own PV.
The remake version features Hinata Haruhana's OC "Master" and the robots (which Len and Rin plays a role in) "Fami" (Len) and currently unnamed robot girl (Rin); while the original version features Len and Rin themselves as robots.
The song tells a story of two robots who wanted to "invade" Master's heart. They wanted Master to open up to her, which was hard at first, though they didn't give up saying they're "elite robots". The robots mentioned how they've been looking everywhere for Master as well.