There are three manga series that revolve around those characters (Yato and Hisako). The first is Kindan No Koi Wo Shiyou, the second is Zoki - Kindan no Koi Wo Shiyou, and the third (which is the longest in the collection of books) Kindan no Koi de Ikou.
The Platonic Solids and Sacred Geometry ~ "Every thought or emotion we produce has a specific geometrical pattern. The more we evolve spiritually the more we see the connection between human evolution and sacred geometry.
"Nyx ~ Goddess of the Night" An original painting by Emily Balivet. Acrylic on canvas, One of the first and most powerful beings in the universe, Nyx is the daughter of Chaos and the sister and consort to the God of Darkness, Erubus.