MIAA-271: 我沒有注意到真正收到姐姐挑釁的處女哥哥是極致的，我沒有注意到爆炸活塞Urara Kanon的爆炸性

I didn't notice that my virgin brother who truly received my sister's provocation was acme, and I didn't notice that the explosive piston Urara Kanon