Day 6 - Most dangerous Touhou.
Holy shit prepare for tl;dr because I didn’t wanna leave out some of them.
Yuugi, definitely Yuugi. Especially for me, since I’m shy. There’s really not much to it, I’m a weak, timid human, and she’s a big, strong oni. There’s no chance that I would come out alive. Even if I didn’t challenge her, she’d challenge me. You can’t back out, of course, and it’s not like you can talk your way out with an oni.
Flan also comes to mind.. While Flan may not be the strongest or even one of the strongest, imagine trying to talk someone with the mentality of a child out of doing something they really want to do (play with you), and them being aware that they have more power than you. The same as with Yuugi, you can’t really talk your way out of this one.
And of course, Yuuka. While I don’t think she’s nearly as harsh as how the fandom depicts her, she’s still a powerful youkai. That and the fact she’s unpredictable and smart makes her pretty dangerous. I have a feeling she wouldn’t hurt anyone as long as they knew their place, but then again her unpredictability is one of her biggest traits imo, so you just can’t be sure about anything. Talking your way out may or may not work, it all depends on luck.
Of course this is all assuming you’re a completely powerless human. Your words are basically your only defense, and when talking your way out doesn’t work.. yeah.