Pretty sure he didn't, it sure seems like it though, my god. Just really bad timing to compare dick sizes right as someone is entering you. I also love the page before that. "You are like a classy maiden" Sure, a classy maiden that gives handjobs to his little brother. This chapter is a goldmine lol
This whole manga is a gold mine. This will forever be my favorite moment in any manga ever: http://www.mangago.zone/read-manga/mahoroba_days/nmt/2577c8f00bb62882/Vol1_Ch3/pg-24/
But yeah on the subject of brother fucking, that unfortunate comparison kinda ruined the moment. Instead of focusing on the scene I was trying to remember if he mentioned anything about his brother doing him. I was sure they didn't but I wouldn't put it past them, they're a weird bunch, which made me doubt myself. Regardless, this manga was enjoyable af, though sometimes kind of confusing.
http://www.mangago.zone/read-manga/mahoroba_days/nmt/v01/c006/pg-35/
Geez Sosuke, is this really the time to start thinking about your brother's dick? (≧∀≦)