Sora no Aosa wo Shiru Hito yo

空そらの青あおさを知るしる人ひとよ

Set in the same Chichibu city as Ano Hi Mita Hana no Namae wo Bokutachi wa Mada Shiranai. its story follows two Aioi sisters, Akane and Aoi, who have lived together since their parents' passing 13 years ago. One day, older sister Akane's ex-boyfriend Shinnosuke Kanemuro, who is 31 now, visits the city to perform at a festival. At the same time, 18-year-old Shinnosuke, called Shinno, also time-travels from 13 years ago. While Aoi starts falling love with the 18-year-old Shinno, Akane and the 31-year-old Shinnosuke finally reunite...