
Yes they are. Have you watched anything regarding hypnosis mic exept for the doujinshis?
”Just like Ichiro, he hates bullies. Due to his big brother's influence, he is well-versed in anime and light novels.”
”Ichiro adores his brothers, Jiro and Saburo, while Jiro looks up to him, basically treating Ichiro as a god for him. Ichiro acknowledges it and worries that Jiro blindly follows him.” ”Ichiro usually reprimands his brothers for fighting for his attention (or fighting in general), saying that they're family and should act like it.”
”Buster Bros!!! is the Ikebukuro Division representative rap group. The group consists of three Yamada brothers, Saburo Yamada, Jiro Yamada, and their leader Ichiro Yamada.”
They all have heterochronomia, their names each contain kanji of numbers (1, 2, 3) based on the order of their births and they have moles that add up according to which son they are born as. Saburo has three moles, because he’s the third son. Jiro has two because he’s the second son and Ichiro has one, because he’s the first born.
Their dad, Rei, is seen interact with Saburo and Jiro in a drama track.
Rei: Hey, hey. There's someone else that could know, yeah? Family isn't just siblings, yeah?
Jiro: Huh…? Our family only has three members!
Rei: So you were just babies carried in by storks?
Saburo: If you're talking about our parents, they're long-dead.
Rei: Hmmmm… Is that what Ichiro told you?
Jiro: That's right.
Rei: In that case, he's a lying bastard. For you see, I... am your father.
And then they proceed to have a rap battle.
Could you really call them only-by-name brothers after this?
Source: hypnosis mic wiki

Dude wtf
Look "sweety" better stfu you sound stupid "i guess", "believe me (▰˘◡˘▰)”
I’ve never seen a hypmic fan as dumb as you, if you even are one. You’re probably just here for the yaoi, which is fine ig, but don’t spread false info
In their songs, anime, and even their appearance they are BROTHERS. They’re little brothers of Ichiro. The three in the division are related
I have never heard that they are not related or they met at the orphanage... Where are you getting this info from???

She wasn't making a big deal about the anime characters. She was mad at how dumb you sound in your comment because of how wrong the info was. (=・ω・=) Also, you shouldn't spread false info. Look at what happened to you. I bet the comment you saw and thought was real was actually false. It made your comment false as well. Then, when other people who don't really know about hypmic reads your comment, they will believe it. The chain will continue you see. ╮( ̄▽ ̄)╭
why is the rating so bad i'm pondering tho i haven't read it..