Muzan Shinigami

the eyes are the gateways 

the gateways to the soul.

    so when the eyes are shattered  what

what do you think is happening to the soul.

   they say you cant break the soul,

but what 

what do you think is happening when you break the gateway,

you are breaking the sheild

the sheild against all the pain and suffering

and so

guess what happens

your soul shatters with it.