From asahi.com:
"A story about a girl being kept in isolation in a world that appears to have experienced an earthquake and nuclear disaster."

Note: Won the Tezuka Osamu New Artist Prize in 2014.

Yuu has spent her entire life with a “copy” of herself, her twin sister. Now science has created a copy more perfect than nature ever could, and Yuu seems like the perfect test subject. But as her copy becomes more intelligent day by day and begins questioning its own existence, the experiment threatens to spiral out of control. Who is real and who is a copy? And what is a “copy” that has surpassed its original? Just a copy, the original, or something else entirely?

The future, romance, everything is "undecided," yet the remaining days of high school seem as if they'll be over in the blink of an eye. Mikako Ichimura, 17 years old. Midorikawa, the strange guy who now sits next to her after a seating change and oddly prefers red pencils. At first, Mikako didn't think much of it, but after learning that they both love the same band, their relationship begins to change bit by bit...

The day to day life of a 17 year girl woven together in a soft literary style.

(Source: MU)