Efficient azacycle (nitrogen-containing heterocycle) formations developed by chemists in Japanese pharmaceutical industries have been selected from the published articles since the year 2000. The selected examples have been classified by the nitrogen source in the raw materials and have been reviewed from the following process chemistry perspectives; elegancy to establish the active pharmaceutical ingredient synthetic processes, logistics to procure/transform the required raw materials, and training for process chemists to consider azacycle formations according to a systematic approach. This mini-review also focuses on the molecular diversity created by the azacycle formations.