Is Kago Shintarou Anime Sakuhin Shuu hentai?
No
Rated R+ (Mild Nudity) on MyAnimeList and not tagged as Hentai.

OVA · 15 episodes · R+ - Mild Nudity
Avant Garde, Comedy, Horror
In these jokey short films, many of them crudely animated, Kago's sick sense of humor reaches its full heights of absurdity. There's a playful surrealist sensibility to Kago's work, as well as a tendency to revel in the ridiculous, the crude and the disturbing. His work straddles a weird boundary between avant-garde experimentation and low-brow fart jokes—the punchline of one of these films is literally an oozing torrent of shit—although, admittedly, his videos seem to lean a bit more heavily towards the fart jokes than his comics. But hey, who doesn't appreciate a good fart joke once in a while? (Source: Only the Cinema blog)
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