Oh, be a fine girl, kiss me.
The sun is a G-type star, according to the usual spectral classes as defined by Annie Jump Cannon in 1901, from hottest to coolest: O,B,A,F,G,K,M.
I believe you're getting this confused with the M-class planet
of the UFP Star Fleet classification system.
A retrograde planet must have taken quite a jolt to get it turned around that way, I wonder how eccentric its orbit is.