Imouto no Mono Hoshige na Shisen

One day, when the protagonist leaves his room, he finds a pink rotor in the hallway. He first thinks it's one of his sister, Ayame, but she tells him it's not her, before going back in her room.
The next day, he finds a vibrator in the hallway. Again, Ayame insists that it is not hers, but the hero turns on the vibrator and presses it against Ayame's crotch from above her skirt. Ayame flushes and goes to her room again.
The protagonist senses Ayame's desire to do something naughty with her brother, but her pride won't allow her to ask him to do it, so he goes to her room and starts attacking her with a vibrator.
What is the end result of this battle of wills between brother and sister?

(Source: GOT corporation, translated)

Note: Published in Comic Grape #50