page 4 : granny is mumbling "four" , it is the 1st number of the code for the safe , but she cant remember the next 3 numbers .
and grand-father were senile : when he was still alive , he locked useless things in the safe . safes are only for precious thing like gold , money . and he could just put the letters and the comb in a normal box or something .
this remind me of this chapter :
https://mangadex.org/chapter/36153/1 .