Hidan is not really immortal

[Untamed]

no body to keep his soul inside means he dies ,so too much lava can rid him of life.. because his body will be completely destroyed.. or maybe his soul will just remain on 'this' plain of existence and not travel to the 'other' world.. where the dead go.

 

[Xāvî1]

we, well most of us already know this

 

[Complex]

He is immortal u_u

 

[DMT]

Immortal or not ..

jashin bless you hidan !