I Am Completely Serious

Nurarihyon no Mago! Well, okay, I've only read the manga, but I've heard good things about the anime. On the surface, it's straight generic shounen -- boy decides to be greatest ____ ever, even greater than his grandfather, boy has to reconcile different sides of his heritage, boy makes friends and fights a lot. But it feels a lot more like a seinen—or even a josei— manga; maybe it's the youkai, maybe it's the way the different parts of Rikuo's life are set up, maybe it's the fact that he won't kill if he doesn't have to, but if he has to he won't even hesitate—no technical pacifism here. Or maybe it's that his Sekrit Identity isn't actually all that secret.

The other one I would really recommend—the one I'm absolutely positive you would like—is Natsume Yuujinchou. littlebutfierce wrote a rec post for it that says all I could and more, but basically it is the nuanced dealing-with-feelings slice-of-life plot-tastic friendshippy shoujo you always wanted. With bonus awesome.