Boku No Onii-chan Ga "imouto Kansatsu Kiroku" O Tsukutte Ita Node Ecchi Na Chishiki Zero No Furi Shite Iroiro Sarechatta Hanashi – Animated

My Big Brother Was Making A “little Sister Observation Record,” So I Pretended To Have Zero Sexual Knowledge And All Sorts Of Things Were Done To Me / ボクのお兄ちゃんが『妹観察記録』を作っていたのでエッチな知識ゼロのフリして色々されちゃった話