俺は引きこもり陰キャ爆乳妹に寝取られる ～私ならお兄ちゃんに寂しい思いをさせないよ…～

"I've always loved you, big brother..."

It was only natural that I, Tsukimino Yayoi, would fall in love with my childhood friend, Ichika.

It seemed she felt the same way, and my younger sister, knowing this, encouraged me.
I could barely hold her hand, but I was happy.

But one day, my sister suddenly became a shut-in.
She became an idol and her passionate love affair with an actor was reported...
I still believed in Ichika. But...

I had fallen asleep at some point, and when I woke up with a strange feeling, my younger sister, Yomogi, was there, straddling me.

"So I decided. I'm going to make you happy, big brother."