This... seems a bit extreme. I never really understood people with armpit or feet or other fetish. Butt or pussy or boob might be a thing... but armpit and feet is just weird. Imagine loving some armpit or feet and then you zoom out to find out it was on a dude.
This is why Japanese media is unequivocally, unmistakably and irrevocably at the top right now, they are the only ones producing REAL ART in the 21st century
A person sat down, thought about it, decided that it's right, drafted the story out, went to a publisher, got it approved and convinced a team of artists to work on this btw.