A few weeks ago I finished Junji Ito's adaptation of Osamu Dazai's "No Longer Human" and wow, that was one of the best things I've read in a while. I strongly considered just immediately reading the original book afterwards but I decided to save that for later this year. Unsurprisingly it's a brutal story, yet despite tragedy after tragedy Yozo Oba's journey is riveting. Dazai's portrayal of alcohol and drug addiction is spot on nailing both the insanity and the humor that sometimes comes from it. Junji Ito also brings his A game, modifying his illustration style to fit the material and doing it perfectly. I'd be willing to call this essential for those interested in pessimistic and misanthropic literature.
Read that one recently myself. Of course it deviated a great deal from the original plot, as it had to (I recall first looking at the length of it and thinking, "wonder what he's added?") considering Junji is more an outright "horror" cartoonist. But it also sticks to the plot very well and introduces some, I think worthy additions, including the change of the ending which I think was very well done (the final picture of the protagonist is excellent). As much as I love the original, I think this "horror-fied" version sits pretty well (a bit iffy about the "descent to Hell" bit, I suppose, but still...). It's been a while since I read the original anyway so for all I know Junji's just picked up on little parts of the story and extrapolated.
Only just recently been getting into Junji Ito's work anyway. "Uzumaki" is one of the best horror stories I've read in any format. "Self" obliterating stuff.