Akuma to Tenshi to Hitotsu Heya no Shita: Sei Dorei ni Sareta Ore

The younger one is naughty, the older one is pure. Now I'm living under the same roof as them and have to obey them... I came back to my hometown to live with my relatives while I attend university. It's been 11 years since the last time I saw them, and my cousins turned into two beautiful women... And Chinami, the eldest, happens to be in the room right next to mine. And so, living with them, my body and I felt like we were in a dream... However, Konomi, the younger sister, was waiting for me with a trap...!! And while Konomi blackmails me into following her naughty whims, Chinami confesses her feelings to me! These sisters mean trouble!
(Source: NUTS!, translated)
Note: Split into 30 episodes on mobile reading platforms.