
as someone with brothers i doubt that it's something that happens often in japan lol

It's just a fantasy fetish. Japanese culture makes higher differences than western from fantasy to reality. So they test the fetishes thoroughly on the fantasy. Precisely because they know it's not going to be true. They don't need it to be true.
And actually that is the main point of all yaoi, since it's not a realistic gay fantasy. It's written by women for women.
The real gay comics in Japan are highly different.

Shota is generally yaoi or shojo and talks about very young boys. Actually I am not even comfortable with that genre.
Bara is the hentai subgenre for men who like men. Get ready to see hairy big men on it.
And if you're more interested in the topic, there are some books about it, like "Massive: Gay Japanese Manga And The Men Who Make It" or check the works of Gengoroh Tagame.
Unfortunately, there is still a huge lack of visibility on real LGTB works in Japan.

I didn't recommend it, someone asked how the gay manga for men are different and generally bara and shota are by men for men. Only reason I said to check it out. It may be bad and disturbing but by men and for men. If you think it's by women and for women you haven't seen the ones by men and for men. Very different and therefore part of the answer to the question on how they are different.

MOSTLY shota is a genre for women. The main genre for gay men is bara.
And this is because shota is related to "kawaii" which is considered way more a femenine thing.
There are SOME shota outside of the shojo and yaoi, but it's not such a trend. So I would not consider it an example of the whole picture.
You'd actually have to search for them actively to find those. Because in Japan there is a comic for every fantasy.
But as a whole, bara was the answer to the question.

I recommend anyone interested in LGBT tv shows watches season 3 of the original Norwegian show "Skam"! Season 3 is from the perspective of a gay guy. He is also a side character in the other seasons.
http://iweb11.mangapicgallery.com/r/newpiclink/thirty_years_old/8/beb256d752de3eaef42fd5965c35a919.jpeg

here are all of the versions with english subtitles! the original norwegian skam is my favourite :)
https://sites.google.com/view/skamsubs/homepage
i need a manga about the bisexual bondage expert