The sea creature was caught over a week ago and pictures of the scary-looking fish have been terrifying internet users when they became widely shared this week.
Wolf fish typically only grow up to 112cm and weigh 15kg, according to the Daily Star, but the one pictured in the recent catch is thought to be over two metres long as the fisherman struggles to hold it up.
This wolf fish could fit a small child into its mouth with ease, although the species diets on crabs and molluscs as a rule.
Chances are this wolf fish got eaten. Hiroshi Hirasaka posted the image on Twitter and he is renowned for catching and eating strange things. He even released a book about his exploits.
The huge catch has prompted questions over the effects of the 2011 Fukushima nuclear disaster on marine life in the area.