Hello
I'm looking for a movie that I only saw once in the 90's. Although I don't remember muc, it's an adult animated movie about a man who's world in witch he is asked by an entity, who somehow resembles a giant brain, to kill him (the brain) in a thousand years or so. Because he is a omniscient creature, he knows he will be corrupted (by himself, I think) and that's why he asks the hero to kill him in the future. He also explains that he cannot be killed in the present. For he is also almost omnipotent in the present, but not in the future. Hence the request to kill him in the future. He gives the hero some kind of poison to infect him, I think. There's also a romantic partner for the hero who's always topless, if I remember well.

Does it ring a bell to someone? I'm having a hard time finding it in the internet, and I would love to re-watch it, as it's part of my early years. Sorry if I can't remember much more.
And thanks for the help.

Sounds like this:

Gandahar (1988) - IMDb

.....It is a giant brain known as the Metamorphis, which has created an indestructible army of metal men to destroy Gandahar. Sylvain must battle the Metamorphis, but not until 1000 years in the future.....

Yes it is! I can't thank you enough! ^^

Perfect!