Natsume Yuujinchou is the tale of a boy who has been able to see ayakashi since young, and hence, been outcasted as a result. He's been passed around from relative to relative, finally landing at the Fujiwara couple's house, where his adventures begin. 

Natsume Takashi is being chased by a youkai when he accidentally breaks the seal placed on a powerful Ayakashi called Madara. Madara has been sealed in the body of a fortune cat and take on the form, following  Natsume around as his "bodyguard" until the day he can get his hands on the "Yuujinchou", also known as the "Book of Friends". The "Book of Friends" belonged to Natsume's grandmother, Reiko, who, upon defeating youkai, asked them to write their names on a piece of paper and collected them to make the book. Soon after, youkai come barging in and disturbing Natsume's daily life and he has begun returning the names of the youkai whose names are in the book. 

There are good youkai, and bad, but what makes the series truly wonderul might be the characters themselves. Natsume doesn't agonise, he's kind, and very in-character. The last season, the fourth, was perhaps the most emotionally moving. I laughed a lot, and cried a lot too. The subtle way it touches your heart is unbelieavable but that's what Natsume Yuujinchou. It's calm, a slice-of-life, and the colours really complement the settings. One thing I love is the relationship between Natsume and his bodyguard, Madara, whom he has named "Nyanko-sensei". You can see how Madara eventually warms up to his human partner, and how his objective isn't actually really the Book of Friends but protecting Natsume. 

The series is episodic and while it's just one event each episode for most of the time, it's very filling. I don't know how to explain the feeling. 

Definitely a series worth watching.