From Baka-Updates:

High schoolers Yuki and Shigeru aren't dating, but still enjoy a highly active sexual relationship. Naïve and still very child-like in the way they think, it comes as a great shock to them when Shigeru discovers she's pregnant. The two are confronted with the decision of aborting the baby and wounding Shigeru, or to keep it and face great opposition from their parents and high school, and *gasp* miss their beloved Conflict concerts!