How many submarines did Japan have?

Japan started the war with about 64 submarines. 41 were modern fleet boats, two were modern medium size boats and 21 were described as obsolete. They added 126 boats during the war for a total of 190. Since some submarines were lost during the war while others were being built, they never had a total of 190 at one time. Japan lost about 129 boats of the 190 total or almost 68%.

This does not include the mini submarines such as those used during the attack on Pearl Harbor or the Kaiten which were developed and used late in the war.