There's an interesting twist in that while Yurara the living girl seems to have fallen for Mei (and he has supposedly the same feelings), Yurara the guardian spirit gets far more screen time and she thinks Yako is much more classy.
I find him grumpy and snobbish in this manga, he was much more interesting in Rasetsu, but I guess that's what the experiences in this series did to him. His nose gets pointed at the fact that he's in love with guardian Yurara and he even gets a kiss from her, unfortunately that means Yurara girl realizes she just kissed the wrong guy ^^. This makes him decide that he better make Yurara girl fall in love with him so she won't feel conflicted and he can love Yurara guardian without feeling bad about it *FACEPALM*!!
A lovely new side character who'll stick around till the end is Yurara's grandfather's spirit sent to look after the living Yurara, since the guardian Yurara is obviously messing up her mission. He's great for comic relief and an observer's point of view to move the story along.
I personally may not like Mei but when Yurara girl really tries to find out whether both boys don't just like the cool beauty Yurara guardian he has a really good answer for which of the girls he fell in love with (although he also still thinks that Yurara guardian and girl are the same person, so it doesn't matter to him in which form she shows up) and when. Kudos, Mei.
Yako's disappointment makes him a dark spirit magnet - that is SO WEAK a plotline, and she'll be using it again! Shades of Luke Skywalker :P At least there's character development for Yurara girl who manages to help a tiny child spirit to pass on without using Yurara guardian's power. Lovely.