Philosophically-wise, the whole story was the most perfect representation of the Yin-Yang dynamic circle, how the concept of opposing forces was brought up between the two. I am convinced representing Ido in a black gown and Sejin in a white gown at the end was not some random choice made by the artist. Being in the same house they would have logically worn similar gowns. The very last panel really symbolised the Perfect Balance and Universal Harmony of Yin and Yang. If you re-read the story with this symbolism in mind, you may view things in a completely different way, and would reflect on yourself as to how to bring the harmony of the Universe within your own heart. The world needs peace. And to bring peace, the people have to achieve harmony within themselves.