They fell in love and they are humans, not old rags.
icky
You obviously don't know enough hot siblings. And aren't a hot sibling yourself. When all three people still get along great years later (not talking about this manga, obviously, the older bro in this is awful), and none of those involved thinks it's icky, that's what actually matters.
But TBH, different people have different things they're just not into and that's okay. I'm not comfortable with big age gaps, when the younger person is a teenager. That's just wrong and distasteful to me, because teenagers are still closer to children than adults in mentality so it's just gross that an adult would be attracted to that. I'm not fond of most studentxteacher stories for the same type of reasons. To each their own.
I might point out that it's not okay to be a dick to/about real people though, oh brave Anonymous.
truuu,, some of us love the idea of fucking the same person as our sibling yummy!! might as well just make it polyamorous and have threesomes all the time amiright??? who needs to choose
what the fuck does hot siblings have to do with anything sdkfhkdhfds im creasing. so youre telling me im gonna see two hot siblings and be like "damn, i just gotta fuck both or else why am i even alive"? also how tf are you comparing a teen dating an adult which is illegal in some places, to something that is just morally dubious and looked down upon in society???? that invalidates your entire argument to be honest lmfao
While I share your sentiment about how it's iffy to end up with someone your sibling already "had"... I also believe when you're deep in love, that shit becomes livable.
I only believe that kind of shit works out when you're real really really in love with the person. Or you have a fetish. LOL.
What makes it particularly iffy, is how it was a bit soon after the older broher... :/
If they weren't really cute and I didn't see them seem like they are gonna be good together, this story would have been a NOPE. Hahaha.

The art is brilliant and the story idea is also good but the idea of sleeping with someone that's slept with my sibling bothers me so much. I'd have liked it if Akihito stepped away after that call with his brother. Can't he be the one being chased for once? I don't know... it just made me so mad. Eh... guess stories where a sibling get it on with their sibling's ex isn't my cup of tea :/