Reddit reviews Gyo, Vol. 2: The Death-Stench Creeps (Junji Ito)

Junji Ito's work has been known to be a little peculiar at times.

I'd thoroughly recommend it (as someone who doesn't even normally read manga).

The one that really gripped my imagination was The Enigma of Amigara Fault - not necessarily the most terrifying overall but kind of played to my particular fears. Read it in English free online here, and if you fancy a copy it was reprinted in English in the back of Gyo vol. 2 - buy online from Amazon UK/US or it will be just as easy to find in your respective country. The main story is decent too - hell, there are sharks with legs at one point (don't mind tumblr link).

The above page is from the second book of Uzamaki, but I'd recommend starting from the beginning if are going to give it a go. The middle of the second volume is where I think it really shines, but you should read what leads up to that if you want to get into it properly. Again, it's fairly easy to find all of this stuff both online for free and in purchasable copies if you like it.

I'm never quite sure on the line between 'helpful' and 'shill-like' so feel free to ignore my evangelizing if your "oh god what" was "oh god I don't like it" rather than "oh god what is this I need to see more to see what other fucked up stuff there is."