Suzuki Shigetsugu served as a bushi and hatamoto during the Azuchi-Momoyama and early Edo periods. He was a member of the Saikatō-Suzuki clan and retainer of the Mito domain in Hitachi Province. He was called Saika Magoichi.
In 1598, Shigetsugu was born as the son of Suzuki Shigetomo.
In 1606, his father, Shigetomo, received a fief of 3,000 koku from the Edo bakufu. Later, Shigetomo served as a hatamoto under Tokugawa Yorifusa of the Mito-Tokugawa family.
Shigetsugu also received a fief of 3,000 koku and served Yorifusa. Shigetsugu accompanied Yorifusa on visits to Kyōto in 1623, 1626, and 1634.
Shigetsugu did not have a natural son so he adopted the eleventh son of Yorifusa named Shigeyoshi. Shigetsugu died in 1664 and his grave is at the Jōkō Temple in present-day Ibaraki.
At the Siege of Fushimi Castle (a preliminary clash to the Battle of Sekigahara), Shigetomo killed Torii Mototada, a retainer of the Tokugawa from Mikawa Province. After this battle, Shigetomo was said to have given Mototada’s armor and swords to Shigetsugu. Shigetsugu later presented these items to Mototada’s son, Torii Tadamasa. Overcome with emotion, Tadamasa gratefully received the items but then later returned them to Shigetsugu, saying that he was very pleased to receive mementos of his father after such a long time, but believed that the items should be given to Shigetsugu’s children and grandchildren instead as remembrances of the military valor of their ancestors. Thereafter, every year, Tadamasa sent a messenger who presented Shigetsugu with a kimono. After hearing of this exchange, Tokugawa Yorifusa arranged for the repair of bridges around the time that the messenger made his annual visit and prepared a banquet for the Saika household.
Torii Tadakatsu, the fourth son of Torii Mototada and younger brother of Tadamasa, headed a cadet family of the Torii clan. Later, Shigetsugu welcomed him as a retainer of the Mito domain in Hitachi. At the same time, he was appointed as the ōbangashira, or commanding officer of reserve forces, so Shigetsugu and Tadakatsu met in person for the first time. At the Battle of Sekigahara, although the two fought on opposing sides, they discussed the coincidence of both having served in important roles for the Mito family.