I really like slow pacing manga, it often refreshing and relaxing... but...
This one, albeit wholesomely cute, has some tiring tropes... the most annoying one is the over-passive MC (doubled as a dumb dumb with a deep lack of knowledge (especially biology)). It's real, without theses spirits, he wouldn't have lived as long (first because he is scared by everything... well, I would too, facing a huge lizard, but, still, Sylphy is there !...) because he wouldn't have known what to do in the fist place... All in one, it's kind of tiring, there is good moment there, but intertwined with several out-of-place considerations and incongruities... That's really drag down the fun =/
Yep, story is good, but I kind of ressent the MC (and Sylphy's condescendant-like personality in some way)... so 5/10 kind of average for me, couldn't help but drop this one, sadly.