If you're on the fence about reading Sundome hopefully I can help you make a decision. Sundome is my all time favourite manga and from over the 10+ years I've been reading manga, this is the most compelling story I have read yet.
The first thing I should mention is that Sundome treads, visually, on the thin line between manga and hentai. However, the sexual content in Sundome isn't its main focus. Sundome is, at its very core, a love story. The crude, raunchy behavior exhibited between characters is all part of a clumsy misadventure originated simply from an interest in the opposite sex. As you read Sundome, characters often develop their own sexual interests, but more importantly, these interests are molded intricately around their feelings of affection. From lust, a genuine desire for companionship is spurred almost instantaneously. The ensuing sexual escapades (and lack thereof) are just an awkward acquaintanceship between two curious, invested individuals. Sex is not presented simply for the pure eroticism of sex. Okada Kazuto uses sex as a chain of intimacy, locking individuals in a loop of dissatisfaction and longing.
Just as a side note: compared to the realm of literature, Sundome is very tame. When you read more and more books, the topic of death and sex are reoccurring and increasingly morbid. Relatively speaking, Sundome speaks of its sexual antics in a light-hearted, comedic style, when you compare it to say, Story of the Eye by Georges Bataille, or even Norwegian Wood by Haruki Murakami.
The real highlight of Sundome, and the reason I love it so much, is how it builds its relationships. When you read it, there is a dark shadow looming somewhere in the distance, a sense of terror that is seeping through each page. The tragedy of Sundome is not introduced in a single chapter but slowly unfolded from its very start. Each action, each decision has a significant meaning, slowly graduating from inane formalities exchanged by complete strangers to highly nuanced glimpses of intimate desire. The sense of demise is introduced fairly early to the reader, and as you progress, there is no remedy for it aside from acceptance. Each time that I read Sundome (I currently had finished reading it for about the 8th time last year), I feel the exact creeping dread that I experienced the first time I read it. The relationships in Sundome, much like its counterpart found in reality, are fleeting, with no guarantee of persisting as long as life.
Sundome is paced perfectly. There is no rushing, there is no dragging. Okada Kazuto took his time telling this story, and I am forever thankful that he did. To end this review, let me share with you how Okada sums up Sundome, and he does a much better job than I:
I want you.
I need you.
I love you.
But I can't touch you.
I say hello...
You say goodbye.
That is Sundome.
I hope I helped you make a decision, even if it was to ultimately not read Sundome. It's a story of frustration and heartbreak as much as it is a lustful account of ones youth. Goodbye everyone, and have a good day.