Am looking for an animated movie from Japan screened in the nineties.
It is a special movie, possibly a combination or tryout in different parts.

A scene: a city destroyed on a planet, greyish and blueish, with lots and lots of robots marching through.
Especially a hoovering robot which is the size of a GIANT, and looks like a sphere. It has another small half-sphere on top of it which can turn around and is its head. (Color is purple/blue or greyish?). The robot has on its head a GIANT RED EYE. It hoovers through the city. Meanwhile a boy (and a girl?) are running to hide from all the violence, robots. They hide behind rubble in a city on a heightened floor (destroyed skyscraper, walk path?) while the massive robot passes them by (it hoovers above ground). You see the robot stop while it is just passing them, and then the head with the red eye (which is a really big light) turns to the couple hiding behind the rubble. The couple flees then, or stays hidden.

Later in the movie the round hoovering robot has in its 'heart', the middle of the large sphere which composes the robot, suddenly a hatch which gives acces to a storage with plenty of missiles, which it fires.

The quality of the movie was pretty good in the nineties, before 1997.
It was an interplanetary setting, with a battlreground on one of the planets, cities which were in flames and destroyed completely. Spacefights, robot fights which were stationed in the thousands. The production of robots went on and on. Music was pretty heavy too.

This movie was released in Japan and not intended for international release at first. It consisted (not sure of this) of three to four parts, each an hour or so.

Would anyone know which movie this could be?
Thanks a lot!