A vassal of the Uesugi Clan, master of Samegao Castle.
At the outbreak of the Otate no Ran after Uesugi Kenshin's death, he fought on the side of Uesugi Kagetora with his troops. After the surrender of the clan's main castle, Kasugayama Castle, to Uesugi Kagekatsu, he welcomed Kagetora and his family into Samegao Castle, from which they would attempt to escape into Sagami. But by the time they entered the castle he had already made a secret pact with Yasuda Akimoto to set fire to the outer citadel once Kagetora was in the castle and evacuate. Kagetora and his wife and children committed suicide during Kagekatsu's general offensive thereafter, ending the war.
There have been no records found of what happened to Horie Munechika after the war other than the fact that his territory was seized.