Ore no Otouto no Honjitsu no Onedari

"I want to have sex with you, nii-chan."That one sentence from my younger brother made my - Ichinose Chihiro's - life do a complete 180.Chikage and I are brothers that get along well.It's been a few years since I started to live together in Tokyo with my responsible younger brother, who is also a mangaka.Is this a punishment to me for relaxing into this comfortable lifestyle?!While I'm stupefied by the sudden declaration of "wanting to have sex," my younger brother approaches closer.Even if he needs it as a reference for his work, w-we shouldn't do such things-!!But if it's my cute little brother that's pleading me so desperately, I might... just give in... maybe...What should I do?!This is a perverted scramble of a battle under one roof!