After graduating from the Imperial Japanese Army Academy in 1911, Horii served in China before undertaking a variety of regimental appointments.

In November 1942, in the retreat from Oivi–Gorari, Horii drowned while attempting to canoe down the Kumusi River to reach Japanese forces defending Buna–Gona.

Born in Hyōgo Prefecture, Horii became an infantry officer following his graduation from the 23rd class of the Imperial Japanese Army Academy in 1911.

The South Seas Force, under Horii's command, advanced using the Kokoda Track to cross the rugged Owen Stanley Range.

[6] By 16 September, after heavy fighting against a small Australian Army force, Horii's command had advanced as far as Ioribaiwa, and was close enough to see the lights of Port Moresby.

Horii decided to raft down the river with a small party so he might more quickly reach the Buna–Gona positions that were being threatened by the Australian advance.