Onii-chan Control

The ending though is a giant cop out. They are in love with each other, but decide to never cross the line and never see other people/get married. They will just live together as brother and sister for the rest of their lives.

I really don't understand how anyone can like incest manga. 😔

Not sure if these were already mentioned :
Yosuga no Sora - In Solitude, Where We Are Least Alone
Seishun Pop!
Ore no Imouto ga Konna ni Kawaii Wake ga Nai and related manga

Old thread resurrected lol. But I remember this shoujo manga that I read that was a definite incest: Usotsuki na Gemini. And some others:

Flowers of Evil (how could I forgte this manhwa, it's the reason why I love incest manga in the first place)
Tenshi Kinryouku

I'm in idol hell T.T

I don't care for incest between brother & sister, but I don't mind it in shonen-ai & yaoi.
Anyway, here are my few yaoi recommendations that I can remember:

Sora o Daite Oyasumi

one twin is in love with the other

Ai to Makoto (Moriyo) this one is an omegaverse story. I don't usually care for omegaverse stories, but this one doesn't seem too bad. Twincest.

Can't think of any more right now

I think it's my first time posting, hope you don't mind the thread-resurrecting!
I have the same taste for incest so thank you so much for the suggestions! I'd like to add some titles:
Saraba, Yoki Hi
Kaori no Keishou

They are presented as step-brothers but eventually find out they're related by blood

Into your heart through the door - this one's with an adopted brother, BUT I like it nonetheless because the struggle and the tension are still there, it's not the usual "oh well we're not related so w/e" - on the contrary, the adopted brother's feeling of alienation from his family because he's not related by blood plays a role too.
Ore wa warukunai - two side characters are half-brothers in love, they have one or two chapters of the main story focusing on them.

I'm not sure but I think Rika the Breeder/Tetsu x Rika has some brothers incest (I read it ages ago)
Lastly, it's father/son but Not Equal is brilliant, and involves time travel so the age gap "in the past" is not that big 😁

I'd be interested in efforts to divide these by genre, like you have the "tomboy sister" Hmanga or the non-tomboy ones... the ones where sis initiates vs when bro does, or when elder vs younger sibling initiates...

-ty