Why does Muzan want Giyuu so much?

But first let me tell you the story of Muzan's lover.

This story will be in two or more parts.

And I researched the eras and Muzan was born under the Engi era

It all starts in the Shōwa era, 600 years before the Taisho era.

Muzan had at that time a lover whom he loved with all his soul who was named Giyuu Tomioka.

They lived happily together but unfortunately one day Giyuu died of an arrow in the heart during a bandit attack.

Mad with pain Muzan immediately killed the bandits and approached Giyuu who was getting paler every second, before he could give his last breath he kissed Muzan and told him that they will meet again in a next life and Giyuu died.

Muzan swore to himself that if there is reincarnation, he will find Giyuu no matter what, even if it should take him centuries, he will not give up until he finds him and is reunited again.

watch?v=ACTmrDuHJXs&ab_channel=Aphonibus

Giyuu will speak the same words to a despairing Muzan, when Lelouch uses his Geass in 1 minute and 44 seconds.

watch?v=-GCd6Q1GT_s&ab_channel=GinpatsuSamurai

I admit it is very sad.

In short since that day, Muzan tirelessly searches for his lover through the centuries while Giyuu at each reincarnation will keep his name and surname, same physique, same personality which will be a little different since he has no memories of his past lives and you will have a star-shaped birthmark on your neck.

Anecdotes: Giyuu liked to watch the starry sky with Muzan

After 600 years of Meiji era reincarnation.

Where Tomioka Giyuu uttered her first cries and the beginning of her story.

I did some math about eras plus Urokodaki's age so that should be it.