Two-dimensional spatial distributions of Hα emitters in protoclusters at |$z$| ∼ 2 on Subaru/MOIRCS narrow-band images. The red and blue circles represent CO-detected and non-detected objects, respectively. The IDs of CO-detected galaxies are noted near the circles. Magenta stars indicate the positions of radio galaxies. The primary beam of the ALMA pointing is shown by large black circles. (Color online)