Puzzled

Upon a time, there was a murderer over the news who has been killing people for over 2 years now. It seems that in all these years the murderer seems to still not be caught yet. A young man named Tantei Hirono is still trying to find this wanted murderer who has been challenging people to riddles and killing the loved ones of the people he/she challenges if they get the riddles wrong. Will he be able to protect his own loved ones, find the murderer unmasked, and stop this massacre from happening once and for all?