Buffets in Tokyo are usually within hotels. And they usually go for around 35-45$ let person. It was worth going there once for the experience, but there are tons of other places you should try out like tepanyaki or the fish market.
I haven't read a yandere manga this fucked up since mirrai nikki. And even that was tame compared to this.
And yes, I know there are other fucked up yandere mangas out there but this is the only one that's compelled me to keep reading even though I wish I could stop....