The reason I became a frivolous, sex-loving man... Real-life version!! Ichika Seta NIMA-021

The protagonist leads a boring life, going to and from school every day. Although there are three busty beauties in his class, they seem unattainable to this effeminate boy. However, he also has a secret. One of the busty beauties in his class, Mizukawa Yoi, is actually his childhood friend, and they even live in the same apartment building. His path of debauchery begins during their practice exams together!