Akizuki Fumitane served as the fifteenth head of the Akizuki clan and lord of Koshosan Castle in Chikuzen Province.

In 1512, Fumitane was born as the eldest son of Akizuki Tanetoki, the fourteenth head of the Akizuki clan and kokujin, or provincial landowner, in Chikuzen.  He became head of the clan following the death of his father in 1531. Around the time that Fumitane took over the clan, he served Ōuchi Yoshitaka, the sengoku daimyō of Suō Province.  Fumitane helped broker a peace arrangement between the Ōuchi and Ōtomo clans.  In 1541, Yoshitaka nominated Fumitane to serve as one of his retainers.  In 1551, a rebellion by Sue Harukata led Yoshitaka to kill himself in an event known as the Tainei Temple Incident, after which Fumitane affiliated with Ōtomo Yoshishige (known as Ōtomo Sōrin), a sengoku daimyō and twenty-first head of the Ōtomo clan.

In 1557, the Ōuchi clan collapsed while the ascendant Mōri expanded into northern Kyūshū.  Fumitane conspired with Mōri Motonari to rebel against the Ōtomo.  Yoshishige responded by ordering Tachibana Dōsetsu and Usuki Akisumi to attack Fumitane with an army of 20,000 men. Fumitane put up stiff resistance from his home base at Koshisan Castle.  However, significantly outnumbered, Fumitane and his eldest son, Akizuki Harutane, killed themselves.  The remaining children were protected by the retainers or fled to the protection of the Mōri.  Upon the death of Fumitane, the Akizuki clan was decimated, and lost almost all of its territory while former retainers including the Fukae clan defended their landholdings to the last.