Also known as: Houjou Tsunanari, Kushima Tsunashige (福島綱成)

Houjou Tsunashige was born son of Kushima Masashige, a vassal of the Imagawa Clan. Most of his family was killed in battle with Hara Toratane of the Takeda Clan in 1521. A family vassal escaped with Tsunashige to Odawara, where he entered the service of Houjou Ujitsuna. His father was killed in the Iwagawa internal discord of 1536 between Imagawa Yoshimoto and his half brother Genkou Etan (there are also accounts that he escaped safely and joined Tsunashige).

Tsunashige found favor with Houjou Ujitsuna, who married one of his daughters to him and bequeathed him the Houjou name. The "tsuna" part of his name also came from Ujitsuna.

When the Houjou began fighting the Uesugi Clan in 1537, Tsunashige participated in many of battles. He continued to be a trusted commander of the clan after Ujitsuna died in 1541 and Houjou Ujiyasu became clan head. In 1546, during the siege and battle at Kawagoe Castle, he held out against an overwhelming enemy force for many months, finally achieving an astounding victory for the Houjou Clan.

In 1571 at the death of Ujiyasu, Tsunashige retired and gave over the family to his son, cutting off his hair and adopting a Buddhist name. He died in 1587 of illness.