As someone who's actually watched this stuff on occasion: I am pretty sure all MLG has is a bunch of kissing scenes. Very romantic, emotional kissing scenes, surrounded by a lot of plot, motivated by many repressed/hidden feelings, secret betrayals, and tragic circumstances.
I would also like to say that even the "porntastic" yaoi stuff tends to have a fair amount of plot. Take the classic
Ai No Kusabi: most of the plot is a string of fairly intense sex scenes. However, the plot is still a PLOT: we have an entire distopian society set up and introduced, we have class warfare, we have gangs and black market scams and discussions about eugenics and social structure and all sort of musings on what makes a society vs an individual strong or weak, etc... and we have a rather lovely forbidden love story. Just... surrounded by a lot of sex.
Or "Fake,"which was generally pg-13, but had some sex scenes. If Hannelore opened it at various points in the manga,
she would probably blush. But it was about two cops solving cases, and each episode had a genuine Law-and-Order type murder/theft/organized-crime/whatever case that formed the main focus of that installment.