From in-game description
"Sword of Honour" - The story:
Shogun Yuichiro's family sword (the Sword of Honour) has been stolen by the power-hungry Damion Toranaga. This means disaster for Yuichiro as his honour is violated. The shogun risk loosing his face in the front of the whole country. Facing the act of seppuku (harikiri) if the honour of his dynasty is not restored, the shogun calls for his most dangerous ninja, warrior, you, to find the damion's secret castle and return the sword where it belongs!
The future lies in your hands...
Sword of Honour is an action-adventure video game developed by Dynafield Systems in 1992 for Amiga, Commodore 64 and PC DOS systems. The game took almost three years to finish.
Sword of Honour combines the action-adventure oriented gameplay of the 1987 game The Last Ninja with the side-scrolling perspective of the 1986 games Ninja (aka Ninja Mission) and Fist II: The Legend Continues, and the icon-based controls of the 1987 game Barbarian. The player fights enemies (either in unarmed combat or with the aid of ninjatō, kusarigama, tekagi-shuko, shuriken and kunai), avoids traps, collects and uses items, and interacts with characters.
The player takes a role of an elite ninja sent for a mission to recover the stolen family sword of the fictional Shogun Yuichiro from a castle of his enemy, the evil Lord Toranaga. The ninja must retrieve the sword and punish Toranaga before Yuichiro will be forced to commit seppuku.
Source: Wikipedia, "Sword of Honour (video game)", available under the CC-BY-SA License.