Messengers to Satsuma

The story

By all indications, an anti-government conspiracy is brewing in the Satsuma Domain. Already seven oniwaban spies sent by the shogunate have infiltrated Satsuma in order to scout everything on the spot. However, they had all disappeared, and it was unclear whether they were alive or dead. Kenzaburo Kamiya and Iori Matsumura successfully infiltrate as the eighth and ninth spies and witness law-breaking exercises using a cannon. However, soon Satsuma men found them and drove them to the cliff...