Car 1 (the Green car) is at the Takamatsu end regardless of direction of travel, so it would be the last car when going to Okayama. If you pick row 1, you will be looking at the empty cab (which I think is better if you want less-obstructed view); if you pick row 9, you will be looking at car 2.

If you want to seat right behind the engineer, you will have be go for the non-reserved seats in car 5.