The Love Tester is a novelty toy made by Nintendo in 1969. Designed “for young ladies and men”, the device tries to determine how much two people love each other. Two people grab one of the connected spherical metal sensors with one hand and hold each other’s hands with the other. The toy then displays the “love score” on a scale of 1-100.
The Love Tester was designed by Gunpei Yokoi (eventual creator of the Game & Watch series and the original Game Boy who said that he “loved explaining that the meter gave better results when people kissed the girl…” It was the first product by Nintendo to use real electronic components and was also one of the few products by Nintendo that was sold outside of Japan during the time period.
Seller says it is a variant, one of three known to exist. No more details on it though.