D
I wonder if all the other Gorosei are named after planets. Uranus, Neptune, and Pluto are already taken, so that just leaves Mercury, Venus, Terra, Mars, and Jupiter. The other 4 Gorosei can be Mercury, Venus, Mars, and Jupiter. Imu will be Terra
It probably doesn’t make sense to western readers but that’s how we name the planets(and the days of the week), Saturn is 土星(Star of Soil), Mercury is water, Jupiter is Wood, Venus is Metal and Mars is fire
Makes sense why they’re called the Five Elderly Stars