I'm looking for a shounen/seinen manga that is centered on the discrimination of people. The main character must find injustice in the prejudices of society and fight against it, much like Lloyd irving in Tales of symphonia or like the blue bloods and red bloods in Seiketsu no Haguruma. I tend to like manga about philosophical and social issues. Romance preferred. Strong leads also preferred. Good art preferred as well.

Being alone is only lonely if you want it to be.
Staying in lucid delusion for an eternity.

There's a bit of discrimination in Mahouka Koukou no Rettousei between the two classes of students.

There's also a category, but only a handful:
http://www.mangaupdates.com/series.html?category=Discrimination

perhaps Liar Game

Orange Marmalade contains the struggle of the heroine with the unjust discrimination against vampires in modern society, also romance and strong leads
sadly it's a shoujo web-comic... would encourage you to read it though, cause despite the romance that's the main theme...

in need of romance?
uncommon, sad, sweet

Rainbow

it's a recurring theme in eden: it's an endless world!
homunculus explores discrimination in society on many levels
in terra e... MU(humans with supernatural abilities) are neglected from society and massacred