Horiguchi Genki was a 5-year-old boy. His mother died when he was born, and he was raised only by his father. His father, Shark Horiguchi, was a professional boxer, but he was ruined and became an itinerant boxer. However, Genki believed his father was strong and he would become a champion, and he had a dream to become a strong boxer just like his father.

After his father’s death, he was adopted by his grandparents. Although they opposed Genki boxing, Genki made up his mind to become a boxer, and he continued training secretly, by meeting with various people.

Azumi focuses upon the life of the titular young female assassin. The manga begins an indeterminate number of years after the Battle of Sekigahara.
As Azumi begins her duty, the manga introduces its characters into mainstream history. Many of the early missions that Azumi undertakes are the assassinations of the prominent supporters and generals of the Toyotomi Clan, against whom Tokugawa Ieyasu expected to again go to war. The manga 'reveals' that many of the Toyotomi leaders who conveniently died of diseases or accidents prior to the final confrontation between the Toyotomi and Tokugawa were actually victims of assassinations by Azumi and her comrades, thus indicating to the reader when the events were taking place.

Note: Won an Excellence Prize at the 1997 Japan Media Arts Festival and the Shogakukan Manga Award in 1998.