The Elder Sister-Like One Vol. 2

Poor Yuu. He’s had it tough all his life. What with losing his parents in a car accident when he was five and being bounced back and forth between relatives with no real place to ever truly call home. He’d give anything for a little companionship and to not feel so alone anymore, and one day he gets even more than he bargained for when he meets a beautiful girl named Chiyo who says that she’ll grant him one wish. Little does he know, though, that she is a powerful eldritch demon known as the "Black Goat of the Woods with a Thousand Young"! What will happen after he wishes for her to become his big sis?! Find out in this ecchi slice-of-life manga by Pochi Iida!
The daily lives of Yuu and Chiyo continue in Vol. 2 of this story of unusual siblings, one of which is a demon from Cthulhu mythology!
Notice: This manga is written in Japanese.