I'm begging for a very old transformation cartoon!

It looked like an invasion, but it also looked a little like a Gundam. The background was that Earth's fossil resources were about to run out, and the environment had become very poor. Once, a spaceship encountered an alien creature (probably a plant…). Then, the remaining survivor would return to Earth. He had forgotten most of the rest. He only remembered the second half. The alien creatures used a method similar to the Nepenthes plant to devour humans and turn them into their warriors. Also, the "transformation system" was something like a four-pointed star crystal. The protagonist's thing was broken when he returned to Earth, so he had to use a huge machine to complete the equipment. I still remember that one of the women seemed to be trying to save someone. She transformed to fight the enemy alone. When she transformed, she held a four-headed cross-shaped Aquatic item. When she transformed, her body seemed to be naked. She wore red armor and later died.
As he was young at that time, his memory was messed up. There should be many mistakes. Those friends who have some impression of him can help him recall.
This cartoon isn't "Universe Knight". Everyone, help me think about it, I'll give you all the points!

Answer 1

As someone who loves reading novels, I don't have the ability to watch animations or provide detailed information about specific works. However, I can tell you some information about the anime. You can find them on the Internet.

One possibility was that Mystic Knight was an animated film produced by Toei Entertainment, which had its premiere in Japan in 1982. The cartoon told the story of a young man who turned into a warrior and fought against evil forces. The cartoon had many loyal fans and was very popular in Japan and around the world.

The other possibility was Sailor Moon, an animated film that was first released in Japan in 1997 and produced by Toei. The cartoon told the story of a young girl who transformed into Sailor Moon to fight against evil forces. The cartoon also had many fans around the world and was hailed as a classic in Japanese animation.

You can also search the Internet for information about other anime transformations to find more works you like.