Gave them a massage. An internal massage.
The question is...has Mitaka-imouto become skilled enough at massage to unleash the Penix?
I feel like "haha you think we were doing something dirty, but we weren't" trope has been done to death so much... that I can't even tell if they actually did it here, especially this lil sister of misunderstandings.
While this is thinking to far into an ecchi romcom gag...
There are massages that involve flogging the recipient to increase blood flow. Granted they usually use bundles of thin sticks or reeds to distribute the force but....
I hate this author so much, if you're going to have a yuri threesome have the balls to show it
Comrade.
Yeah, she owns a crop just to troll, sure. I bet she trolled her friends so hard.
No no its to use on Bro. Or maybe for Bro to use on her.
Don't want to break your disillusion too much, but im pretty sure the sister is a huge brocon, borderline incestuous sister, and she just like to troll her brother. I went on the author twitter to try and learn more about the two gyarus, and while they seems to like or love the sister, she doesnt seems to reciprocate their feelings at all (tho its true she is a total chicks magnet like her brother and could probably create herself a little harem)
https://x.com/i/status/1924747431109181579
She's a huge brocon and daddy's girl, to the point mom gets jealous of the latter.
Obviously the imouto's plan was
Have Gyaru over, get them to moan and be noisy -> Brother thinks they are being naughty -> Bro gives Imouto Correction using the handy horse whip the imouto brought from mom and dad's bedroom.
that's why the Gyaru give him that look for two panels. They are getting to see what all the fuss is about.