As stated before, only those with strong spiritual powers can see youkai. Youkai all have their own personalities and unique abilities attributed to them. They have diverse habitats and diets. Many feast of fruits, vegetables, and fish but some have developed a liking towards human flesh, especially towards those with strong spiritual powers, noting that they "smell yummy."
Youkai's appearance ranges from humanoid forms, to shapes, to poofs of cloud or dust, and sometimes strange figures. Many closely resemble animals but are instead, bipedal and even have fur; roughness ranges from very fluffy and soft to crinkly and brittle.
Some are very beautiful and others, the opposite.
Youkai temperament is just as diverse, plenty are hostile and have a strong hatred towards mankind. They often mention the deliciousness of humans and those who have strong spiritual power. Whereas others are kind and gentle with a strong sense of duty and are respectful. They also have insecurities and although they claim to not understand human feelings, it is shown that they tend to display human feelings. Natsume has pointed out that they are a nuisance at times and often find joy in messing/tormenting those who can see them, especially when they're young.
Reasonably, they hate and fear (dependent on their level of power/personality) exorcists. Many steer clear or scatter when they hear an exorcist is nearby.
There are youkai that are pure evil, finding joy in tormenting and killing humans and even other youkai. One example is Sumie, she was encountered in a hot spring inn where she once terrorized people who visited. Her head was sealed in a jar but the rest of her body escaped. She was powerful enough to break the sealing on her head and when she lied to Natsume so that he would return her name, she wasted no time in attacking and trying to eat him. She was ecstatic to know she'll have a meal and didn't hesitate to express it.
Another notable youkai was the one that was sealed away, below the earth. It lacked intelligence and verbal capabilities. It reeked poison and if left to reach the surface, it would've destroyed anything and everything. It was merely a mindless, rampaging monster.
But the most common thing to all youkai is how they request assistance, through threats (and/or kidnapping) rather than simply asking. Mostly seen from the youkais that request Natsume's help.
Powers & Abilities