This will be the fifth Korea-Japan joint workshop on Dark Energy, celebrating Prof. Alexei Starobinsky' 70th birthday. Dark Energy is one of the biggest puzzles of modern cosmology and theoretical physics. We will discuss the most recent advancements in the field, focusing on both theoretical and observational aspects. We will not restrict the topics of the workshop to dark energy only, but we also welcome talks on quantum gravity, modified gravity, inflation, gravitational waves, cosmic microwave background, large-scale structures, and dark matter.