I'm not sure there have been large sharks 25+ feet recorded.  Which would make them larger then the one in the jaws movie.  I also have read stories about huge sharks coming up out of the Marianas Trench but theres no confirmed sightings of them.  I doubt that it would be a Megalodon it is probably just some unknown deep sea shark.

Don't understand Japanese but it looks like a whale shark to me...longer than 40' have been seen.  They also do not attack man that I know of. 

Sleeper Shark. 

Well i have seen a whale shark and that is not one. Besides they eat plankton. This a deep water sherk, but not sure what the name is.