Bakajo 26-ji

Atsuko and Yuri were classmates from elementary school all the way through college, although they hardly ever spoke to each other during their school days. At their first reunion in 15 years, Atsuko discovers Yuri's secret, and she takes drastic action.... What will be the destiny of these two polar opposites, who have completely different interests and friends, and whose personalities often clash?

(Source: Pixiv Comic, translated)