ROBOT 5 PINK VERSION - SANKEI - JAPAN
The pink version had on the bottom of the box the word "red" stamped. The box is a special two piece Sparkling Mike version
The grey/black had the word "black" stamped on the box bottom.
It is believed that the pink variation started as a black/grey with a pink coating then applied. No two pink versions are exactly the same hue and this may be due to the way the pink coating 'cured'.