On April 16, when 2,400 newly Japanese troops landed in Esashi, the reinforcements consisting of and soldiers were dispatched to the area, and their ammunition and food were also supplied. On the other hand, the Japanese Army, keenly aware that it is not easy to pull out the bifurcated base, would begin to march on an open road from to over the mountains from April 17. It was a strategy to send soldiers and ammunition from here to attack the fort from behind the Shogunate forces, but this plan was also extremely difficult. During this time, two platoons of trainee officers led by Mitsutaro Takigawa have been strengthened in the former Shogunate army. On April 23, the battle began as the former Shogunate army's repulsion approached the Tenguyama position of the Imperial Japanese army guarded by the troops of the .