晴れた日に絶望が見える by あびゅうきょ

While this one is not properly a dōjinshi, it comes from a mangaka I first encountered through their dōjin work, sooo... I arbitrarily decide that it still counts. Plus, in the case of あびゅうきょ, there is definitely a continuity in themes and graphic choices between 'official' and 'self-published' outputs, as they tend to wander around the same handful of bizzarre obsessions - mostly guns, girls, and the otaku world.

晴れた日に絶望が見える is an actual manga, a one-volume thing published through Gentosha Comics, a publishing house mostly (but not exclusively) geared towards the seinen (adult manga) business, in past years through their recently defunct Comic Birz magazine.

晴れた日に絶望が見える (I can see despair on a cloudless day) comes, however, from a far distant past - 2003, to be exact. It's also one of a series, which counts three volumes and goes under the bizzarre title of 影男煉獄シリーズ - something like 'The Shadow Man Purgatory Series'. In reality, each volume, including the first one, is made up of mostly independent one-off stories, accomunated by their shared protagonist: the Shadow Man, a figure covered head to toe in a black drape.

Each story follows more or less the same structure: the Shadow Man embarks on a conversation with a girl he encounters, a conversation that usually turns into a verbal chastisement of the Shadow Man's innumerable shortcomings and faults, as the two wander across landscapes ranging from a destroyed city to an idyllic playground. There is little plot to speak of: the manga's meat is, through the means of dialogue, a Kafkaesque indictment of human nature, with especially pointed retorts against the stereotypical shut-in otaku that, most likely, hides under the shadow man's draperies.

A one-shot is also included, a bizzarre pseudo-historical account of a young girl... who happens to be an ace pilot under the Third Reich. Yeah. In his work, あびゅうきょ is no stranger to fetishization of the seedier aspects of military history, so this weird snippet didn't come as a surprise - you either take it for what it is (and what is it? a tongue-in-cheek joke? actualy historical interest? some bizzarre pastiche) or move on.

Visually, this volume falls in line with あびゅうきょ's usual style: extremely detailed backgrounds, obsessive attention towards the minutiae of military machineries and uniforms, cute girls who tend to be on the stockier side. There is also an aboundant use of unusual perspectives and points of view, including fish-eye lenses.

All in all, another strange trip from the mind of a mangaka who has made weird fixations the pivot of their work. Reccomended if you're into the more bizzarre side of seinen. 

P.S: there is a video trailer for 晴れた日に絶望が見える. You can watch it here.