So, I can't suggest Karakuri Dôji Ultimo
enough. A collaboration between Hiroyuki Takei (creator of Shaman King) and Stan Lee (creator of basically all the silver-age Marvel heroes) is a recipe of awesome that pays off!
I'm also podding the recommendation for Fullmetal Alchemist
and Katekyo Hitman Reborn
. If she liked Soul Eater
, she'd probably also enjoy Blue Exorcist
, and if you can manage to find it, Yuu Yuu Hakusho
is a classic and still one of my favorites.
And if she's looking at online comics, then she should DEFINITELY check out Gunnerkrigg Court