Avant-garde Yumeko is about a teenage girl who uses her art to manifest a growing interest in the male body and sex. Whenever she thinks of or sees a dick, she gets the urge to draw! And her work is quite impressive.

This concept could easily be turned into a hentai. Knowing this medium, it probably already has. Oshimi Shuzo is more concerned about the importance of art in the hands of someone who needs a way to channel their curiosity in a private and productive activity. Needless to say, sex is a really hard thing for teenagers (and even adults) to talk about openly - many never have any sort of education or "talk" from their parents to prepare them for what their bodies are designed to do. This manga presents a constructive solution to that curiosity that I found to be quite endearing and funny. It's probably relevant that Japan's obscenity laws prohibit depictions of genitals in their media, further limiting the agency of a teenager to learn about sex through the media they consume. Yumeko then has to satiate her curiosity through her own imagination, and with the help of a willing male club member.

That said, there are a lot of drawn dicks in this manga. So I can imagine readers being too grossed out to even care about what themes are being conveyed. It doesn't help that this is an early Shuzo work before his art style became more refined as it is now, making it a bit harder to take seriously and to identify what the point of the story is.

Personally, it didn't bother me enough to take away from the enjoyment of the manga. and I find this to be a good precursor to later works with similar tropes that you may recognize as a fan.