 If you liked
Shugo Chara!
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 ...then you might like
Kami nomi zo Shiru Sekai
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These are really different but they have one major similarity. In Shugo Chara people create those X eggs because they can't do their dreams or something like that, while in Kami nomi zo Shiru Sekai, people get loose souls because of something emotional inside them too. And it's up to the main characters to solve that.