Shūzō Oshimi is a name synonymous with taboo. His most well-known work, The Flowers of Evil, begins with a high school boy stealing his crush's gym clothes, and from there roars headlong into the throes of obsession as its troubled cast suss out the darkest parts of their psyche. That same energy is oppressively present in this inaugural volume. Inside Mari begins by locking the reader inside the psyche of Isao as he recounts his depressive descent from bright-eyed college student to disheveled shut-in, and in a deeply unsettling sequence, shows us the twisted knot of emotional projection that leads to him stalking his “angel” as a nightly ritual. The manga makes it clear from the opening pages that this is going to be an intense journey through thorny, provocative topics, and it's not likely to pull punches as its frankly contemptible protagonist pieces together the central mystery.

Though it hasn't quite gotten there yet. Oshimi's other defining trait as an author is his penchant for slow-burn narratives. Once Isao has come to terms with his supernatural situation, the remaining chapters are largely built around his flinching, clumsy attempts to play the part of Mari despite knowing nothing about her. The most meaningful scene comes as he walks his new body to school, and becomes cognizant of the near-constant gazes of the men around him, realizing in the process that Mari must have been aware of his attention as well. Oshimi mentions in a rather illuminating afterword that the impetus for this story was his desire to understand the perspective of women, and that's most present as Isao experiences the mundane life of his “savior” and slowly learns who she was before he seemingly usurped her body. What kind of student is she? How does she talk with her friends at school, or her family? Who is this girl he's spent so long obsessing over? These are the small details that make what could otherwise feel like aimless chapters into building blocks towards larger questions of identity and perspective that the series will presumably explore later on.

Much of how readers react to this volume will depend on how much of Isao they can stomach. He can internally insist he isn't a stalker all he wants, but following a teenage girl home every night is just the tip of his unsavory personality. While changing clothes in Mari's body he keeps his eyes closed because he hasn't “received [her] permission yet” and that “yet” is an absolutely load-bearing modifier. When he breaks down in tears and one of Mari's friends hugs him, his first instinct in response is to grope her butt and fixate on their chests touching. To be sure, the series doesn't portray him in a positive light, nor does it invoke the harmless pervert trope or anything of the sort, but instead treats him as a brutally honest incarnation of the kind of man who fetishizes teen girls' bodies. However he's still the central character, and if the idea of spending hundreds to thousands of pages inside his brainspace puts some off reading the series, I can't blame them. It's perhaps a compliment to the level of Oshimi's character writing that he can so effectively capture the toxic impulses he imbues his cast with, but much like well-made horror fiction, that in itself can be a double-edged sword.

That said, the volume does feel a little lacking in terms of payoff. Obviously the larger mystery of how and why this body-change happened isn't going to be solved right away, but between Oshimi's sparse dialogue and somewhat repetitive middle chapters, the end of the volume arrives just as it feels like the story is starting. The only major shift in the status quo is the late introduction of Yori, the only classmate of Mari's to see through Isao's clumsy facade, and while her involvement both raises questions about her own relationship with Mari and promises to move the story forward, it also comes only a handful pages before the back cover. There's a certain amount of enticement to that pacing, but combined with the lack of progress preceding it, it also feels frustrating, especially if you don't already have the next volume on hand.

Still, wanting more is the right kind of problem to have with a first volume, and those familiar with Oshimi's other works are likely used to it by now – Happiness likewise took until its second volume to really come into itself, and Inside Mari seems to be similarly building towards its real identity as a story. For those with the stomach for living, however briefly, inside the mind of its protagonist, this is a strong introduction – if not always a pleasant one.