Red Blood Cells (RBCs) have an important role in delivering oxygen in our body. To efficiently flow to capillary ends,  RBCs change their shapes in response to various blood flow conditions. Also, they flow with a cell-free layer to reduce the resistance to vessel walls with complex interactions. However, it is challenging to understand the dynamics of RBCs in the human body due to the limited accessibility in experimental measurement. Therefore, it is helpful to use computational models with cellular interactions. The purpose of this research is to simulate deformation and flow of RBCs in a single bifurcated vessel, as a representative model for understanding the dynamics of RBCs at network level. The transport of RBCs in a single bifurcated vessel is compared with 'in vivo' data and theoretical models, which was mentioned in our previous research, related to fractional blood flow. An immersed boundary (IB) method is used to simulate blood flow with individual cells and plasma in a single bifurcated vessel. Also the deformation of RBCs is estimated by a spring network model. We carried out simulations at two hematocrit levels, 10 and 20 %. Based on the simulation results, we will discuss the resistance by RBC transport at the bifurcation point and quantitatively express the plasma skimming effect.