lifes full of glitter~!!!

During the Far Shore arc, Hanako made it clear that evil spirits and supernaturals go wild for the soul of a kannagi, meaning equally they eat regular humans as well. The only difference being that they are not considerd a special meal. Of course, many other chapters divulge on this topic. But that aside- this overall indicates that consuming humans is their source of fuel to exist.

But have you considered what Hanako did during the 50 years he's been bound between life and death?

For Hanako to even be regarded as the leader of the seven mysteries, and held at a high degree by Teru Minamoto suggests that his sealed ability outmatches the rest. And considering how he is essentially the 'baby' of the seven wonders, this makes it even more interesting. Being an evil spirit with a murder on his hand doesn't really explain his current position, seeing how Hakubo killed plenty more people, so if it's in the sense of a crime it wouldn't really add up.

So what did he do during that time? Maybe that links to one of the reasons why he was sealed in the first place.

In actuality, it would connect more with the Hanako-san folklore of consuming humans. Perhaps the manga didn't deviate too much from it's original folklore as many believe, seeing how he died in the same period as the original Hanako-san, and committed suicide (which was one of her potential ends). Additionally, the pilot version stated that they consume things without form, so that suggests that consuming the lifespan of a human is possible too (and now thinking about it, the clock keepers arc demonstrates that too with the owls...).

On that note, even if Hanako didn't consume humans- I believe he would have at least eaten a supernatural since Mitsuba is essentially almost the same as him (both humans reborn into one of the seven wonders).

And that brings me to Tsukasa:

He knows a lot about a supernaturals' appetite. Supernatural creatures eat eachother:

And that made me think, Tsukasa died when he threw himself into the hole. So in that sense, being dead, he doesn't need to eat anything. But when Kou is there at the read house with him, we see them both drinking.

The house brings you whatever you wish for. That is, if you give it something in exchange:

However, Kou didn't make an official wish and yet, we see both of them later drinking, something offered by his mother (who is clearly just the red house/entity playing mind games and not actually her), so without conducting a proper exchange, what's to say that what the house offered; whether it be food or drinks, is normal and considered edible in the human sense and not something else? Tsukasa was offered a drink by Kous' mother, so essentially the entity provided it to him- but that's not really necessary is it? Seeing that he is already dead and his soul had been collected (not unless it has a plan for Tsukasa from the very beginning...).

Maybe that's why, other than spending time most of his early childhood amongst supernaturals, he knows a lot about their appetite.