So when i was first reading the Sailor V manga i noticed that Saitou, the guy Minako had a crush on looked like Kunzite. And then two days ago i found this:

Is Saitou really Kunzite in disguise? he was mentioned by Danburite in that chapter

Queen Beryl was originally an ordinary human who later awakened to her memories so I suppose it's possible the Shittennou were all reincarnated as ordinary humans too.  On the other hand, Naoko also recycled a lot of her character designs from Sailor V in Sailor Moon, so she could just be using the same design, like how Minako's friend from Sailor V looks a lot like Ami.

The musicals actually used the name "Saitou" for Kunzite's disguise. I think this happened at least twice, though I don't remember for sure.

Sailor Mercury wrote:

The musicals actually used the name "Saitou" for Kunzite's disguise. I think this happened at least twice, though I don't remember for sure.

Nods. 

Also, if I'm not mistaken doesn't Manga!Saitou end up with some other girl?

He ended up with his old high school teacher that he's always had a crush on, I think.

I always thought they were two different characters since naoko likes to use the same designs for different characters. 

Though this gives me a heartbreaking theory now...

Whats the theory Cosmos?

Well, you know how beryl was (in the manga, anyways) just a normal human until she resurrected her memories when stumbling upon D-Point? What if Saito was Kunzite, just reincarnated like the rest of the cast? Then after Beryl did her thing, Saito was fed false memories/altered memories and just abandoned his civilian life-and his love because she would have warped with his mind that badly. 

But even with new memories, someone wouldn't just up and walk away from their lover. So that gives this theory wiggle room as to what Beryl could have pulled to have Saito change to the dark side. She could have found a way to break Saito's spirit if he put up resistance to her interference-most likely involving his teacher. There are multiple ways I could go with this theory, either way, it's gonna be tragic as sin.