Jellyfish and Coral

Kaizuki Shirahase is an ordinary, 16-year old, first-year high school girl. Her twin sister, Sango, is beautiful and smart, but she can also be a problem child. Not that Kaizuki doesn't like her sister. But it's a little complicated because Sango is always pushing her around. Kaizuki's been living her whole life worrying about Sango, until she fell in love. A complicated love story of twins! (Source: Betsufure, translated)