the hand is yoseob's imagination. He has a hallucination of himself with many holes on his flesh
here, the full pic of his hallucination, this is from the korean raw on lezhin (free for now) https://www.lezhin.com/ko/comic/another_secret/34?requiredCoin=3&target=charge-coin
that's what I thought.. thanksssss ┗( T﹏T )┛ but i can't open it it says something in Korean and I don't know which one to choose
if you already had an account on lezhin and the account's default language is english, it's asking you to change the language to korean ( because the raw is in korean only).
You can open the chapter by clicking the left one (that's the approve option) but before that, remember to open your account setting in "my account", memorise the language stting's locaction to change the it back later
*setting*
it might be jaeha's hand( I'm like 50% sure). but I don't think it's yoseob's, he can't has his own hand on his back. or maybe it's just in his imagination