"Does anyone know Japan's fuel stock toward the end of the war?"

Probably depends upon whether we mean the home islands or possessions. The fuel shortage in the home islands was critical. At Okinawa, there was enough oil to send Yamato on a one-way sortie against allied forces, and enough gasoline for one-way missions of suicide aircraft, and not much more.
The fuel situation in parts of China and the Philippines might well have been otherwise.

JT