Well, it could sound weird, but I liked the way the story works when the protagonist has little/no memory at all of his/her past. (Also I cant believe there wasnt a "Memory Loss" tag, I added it at the series I know there is, like Burst Angel, Sankarea, even if in minor quantity and towards the latest chapters,..).

PS: I noticed too late that theres an "amnesia" Tag in Elfen Lied, and probably alot more mangas, so I wonder if I was too stupid to create "Memory Loss" Tag, or it could be a good one to place togheter with "amnesia" as an alternative Tag search (in the end it could be useful to search more easily).
If "Memory Loss" isnt good, I apologize to the staff and the users of this site, I am really sorry

definitely Tripeace he has absolutely no memories of his past at all (not even his name if I recall correctly)

Good, I'll give it a try when I return home. Thanks

Loveless. The protagonist inexplicably only remembers the last two years. because of it, even his character has changed completely. and it's my #1 favorite manga
p.s. it may sound weird at first chapters but you'll Love it when you reach chapter 5. (unless you REALLY hate shounen-ai)

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the Truth remains intact...

Well, Im dont really ..simpathize with gay stories, but I am used to don't judge a book by its cover, so Ill give a try and let you know

Even if its not related, I just wanted to say this: I dont like love between cousins, but I wasnt annoyed at all when I find this theme in the mangas I read, if its useful for the story, and also I used to avoid shojos, but I read all Watashi ni xx Shinasai! and I liked it, I was surprised because I am not used of such a genre.
Just saying, I read like 10 chapters before deciding if I have to continue or not, and what counts is if it entertained me or not, if I liked it and then I continue reading, or I feel like I am forcing myself and then stopping reading it

GUNNM... I would suggest to NOT read the last volume of GUNNM and instead start with GUNNM: Last Order from there. She doesn't remember anything, but some things she subconsciously remembers (mostly fighting).

Tasogare Otome x Amnesia. Well... it's right there in the title so...

Watashi no Taisetsu na Tomodachi. Friend loses memory after a weird accident.

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~4400 manga completed
~1700 ongoing...

Saihate no Ao is recent and only has 2 chapters out so far but it looks promising

Oh great, I am surprised by the amount of replies
Really, thanks you all

I had some time and read Tripeace to chapter 7, drama and comedy at the same time, I like it!

For the other titles Ill read them now and tomorrow morning (its almost midnight here lol), and thank you again