It is only fitting that I make a calc about bones during spooky month.
As stated here, Mori can sense people entire solar systems away but couldn't sense the bottom of the Heavenly Realm. He can stretch Yeoui down 9993 floors of the planet, each being described as being a world onto itself. Given the context, I will do 2 calcs based on the 9993th floor being a solar system distance away and each floor being Earth sized.
I will be adapting this calc and using this calculator.
Solar System Away Distance[]
Nearest solar system is 4.1343e+16m away.
If we assume the pool at the top is Olympic sized, and Yeoui is as dense as graphene:
Mass = 2.267 x π x 12.5^2 x 4.1343E+16 = 4.60069461E+22 kg (Class Z)
Each Floor Is A World Distance[]
Earth's diameter is 12,742 km.
12,742 x 9993 = 127,343,548 km = 127,343,548,000 m
If we assume the pool at the top is Olympic sized, and Yeoui is as dense as graphene:
Mass = 2.267 x π x 12.5^2 x 127,343,548,000 = 1.41709304E+17 kg (Class P)
Bonus[]
At the end of the latest chapters, Mori became strong enough to wield 21 Yeouis (The 19 Dragons, the original Yeoui [Ogre], and Dragon [his brother])
Low-End: 1.41709304E+17 x 21 = 2.9758954e+18 kg (Class P)
High-End: 4.60069461E+22 x 21 = 9.6614587e+23 kg (Class Z)