Martial Arts on Japanese warships
Just as Western Navies had boxing, and shooting teams and practiced bayonet drill regularly for use in landing parties, and fencing was seen as a manly right of passage in some modern countries even into the 1900s, the Imperial Japanese Navy likewise drilled their own martial arts on board ship in the years between the 1850s and 1940s.
Kendo being practiced on the deck of an unnamed Japanese battleship as crew watches on, 1915.
Martial arts matches aboard Japanese cruiser, perhaps a Myōkō-class heavy judging from the twin aft turrets. Note the judo on mats to the port side and kendo to the starboard side.
Although this is a relatively old post I still would like to point out that the turret in the second pic doesn’t resemble that of the Myouko class, or any heavy cruisers of the IJN. It should be one of those 140mm twin mounts used on the Yuubari and the Katori class. And according to the stern shape and the two barrels above the turret I would suggest that this is a Katori class training cruiser. However I cannot specify which (Katori, Kashima or Kashii).