Murakami Ryota's best friend, Kuroneko, died in an accident trying to prove aliens existed when they were kids. Now, a girl who looks just like her transfers into his high school. When confronted Kuroha Neko insists she isn't Kuroneko, but she ends up revealing something else even more surprising...
Now that Murakami knows Kuroha is a lab-made witch on the run, he can't just leave her to fend for herself. Overcoming rejection, he manages to learn a bit more about her living situation... and her companion.
Having overcome the immediate death suppressant shortage issue, the witches start to settle into their lives as astronomy club members. A visit to the local onsen ends painfully for Murakami.
The gang waits out the result of Kogoro's initial analysis of the pill to find out if he'll be able to copy it in time. Neko tries karaoke. Murakami and Kazumi head to Akihabara.
Lab witch Nanami and her handler are looking for #1107, but Ryota and the rest wonder whether they really have to be enemies. Couldn't they rescue her instead?
Kogoro is enlisted to attempt to remove the beacon from Nanami's harnest. Later on, Murakami motivates the girls to study for final exams by promising them a trip to the ocean.
The identity of #1107 and the objectives of the witch lab are revealed as Murakami and the rest work not only to save themselves, but suddenly the whole planet.