Now for let's fantasize about a fantasy world. Even if it's impossible. How would you guys quietly snuff certain characters?
If I saw Cirno like this I'd grab her and drag her away from her group in deep grass before a silent but brutal crack stops her struggles~ then take her outfit and wear it as disguise and go for more kills~
>>41324 Cirno's dress probably wouldn't make for a very good disguise, especially if you take into account the fact that sooner or later she'll come back, and probably spread the news around that some crazy guy assassinated her. If you're looking to do things quietly, your best bet is to stick to anything that won't get better afterwards, and even then between the influence of certain youkai too powerful for you to pose a threat to, and Reimu's instincts clueing her in to the fact that something is up your days would be very shortly numbered. My best guess as to an ideal target would probably be anything you're likely to put out of commission with a long sharp stick. A kappa/yamawaro if you can somehow catch it unawares, or maybe Rumia. Avoid Youkai Mountain and the underground like the plague especially, given both are crawling with powerful and deadly youkai.