Class no Yuutousei wo "Imouto" ni Suru Yakusoku wo Shita. Douyara Ippai Amaetai Rashii.

After an disagreement with his father, Ryuuki Takato ran away from home and was rescued by his classmate, Ao Kakogawa. He ends up staying at the Kakogawa household, but as part of the arrangement, he has to form a ‘family contract.’ To his surprise, Ao, who is known as a model student, starts acting like a clingy ‘little sister’ at home—what’s going on!?