Ok let’s look at the reaper death seal this is a s rank jutsu developed by the uzumaki to summon the Grim Reaper and I mean that literally this is the actual grim reaper of the Naruto universe now how people figured out to move there hands to summon a god is Beyond me but it happened so anyway after the grim reaper is summoned the users soul is held above them by the grim reaper

In exchange for giving the reaper your soul he will seal the soul of whoever the caster chooses and seal it in the stomach of the reaper themselves or someone else this is how minato sealed the nine tails in himself part of himself himself in Naruto and part of kushina in Naruto also to put into perspective how strong this thing is the reaper split the nine tails soul in to to separate beings with his sword to put this the only other person to split tailed beast was the sage of the six paths now back to the justsu when the reapers initially summons no one will be able to see it besides the jutsu caster this means it’s is significantly easier to catch someone with the reaper so after the jutsu caster has made contact with the person they want to seal the extraction of the soul begins something I want to say is you don’t need to be kissing like orochimaru and hiruzen as the reapers hand can go pretty far

the reaper wraps a bead necklace around his arm and a Curse mark like the pattern will spread on his arm he will begin to Chant and start to extract the soul
as soon as the reaper starts to extract the Soul the person who soul is getting extracted will be able to see him this isn’t really a problem however because one look at the reaper caused orochimaru to sh$t himself the same orochimaru who with no arms was laughing at four tail Naruto so the fear caused is pretty severe and the person who cast the reaper will not feel the fear also while the reaper is grabbing your soul you can’t move for the most part orochimaru could only mange to move his fingers a little bit which luckily for him allowed him to call his sword back to him impaling hiruzen this caused him not to be able to fully seal orochimarus soul but since the reaper can cut souls with the blade he holds in his mouth he cut orochimarus arms out of his soul

By doing this orochimaru could not use his arms and caused him to have excruciating pain until he released his soul from the belly of the reaper this pain was so severe that he had to switch bodies every two years and it always came back this pain was so excruciating that if he didn’t have this ability he probably would’ve died to the pain needless to say a normal person would die if any part of them was sealed
Also I would like to say that this is super impressive because a old tired man who fought two other kage and was stabbed in the back was able to do this seal
On on that note yes there is a way to release souls from the belly of the reaper there’s a mask that exists in a uzumaki Temple Once this mask is put on the reaper possesses it’s where are and the person can controls everything he does at this point including cutting its stomach open and releasing souls
Also whatever soul that is sealed goes through incredible torture that’s why orochimarus arms hurt so much