What's the worst tbhk volume in your opinion, and why?

For me personally, its volume 5 because a lot of it seemed very....unnecessary? Like yeah I get it, we meet the clock keepers and find out Akane is a clock keeper but stuff doesn't get serious til volume 6 or so. Plus imma be real with you, the whole possessed Yashiro seemed very iffy to me, like it just came out of nowhere really.