Lifespan: Tenshō 10 (1582) to 10/13 of Keichō 19 (1614)
Other Names: Yasuuji, Mitsuuji, Ujimitsu, Yoshinari
Clan: Dewa-Shimizu (an illegitimate branch of the Mogami and offshoot of the Narusawa)
Father: Mogami Yoshiaki
Mother: Tendō-gozen (daughter of Tendō Yorisada)
Siblings: Yoshiyasu, Iechika, Shimizu Yoshichika, Yamanobe Yoshitada, Kaminoyama Yoshinao, Ōyama Akitaka
Shimizu Yoshichika served as a bushō during the Azuchi-Momoyama and early Edo periods.
Yoshichika was born as the illegitimate third son of Mogami Yoshiaki, the sengoku daimyō of Dewa Province. His mother was a consort named Tendō-gozen. He was the younger brother of Mogami Iechika and the father of Shimizu Yoshitsugu.
Yoshichika was adopted by Shimizu Yoshiuji, the sixth head of the Dewa-Shimizu clan, who did not have a natural son. The Shimizu were an illegitimate branch of the Mogami and offshoot of the Narusawa clan. Yoshichika governed a territory of 21,300 koku. He is surmised to have received a character in his name from Yoshiuji and adopted the other name of Ujimitsu. Later, he was placed under the command of his oldest brother, Mogami Yoshiyasu, and, after receiving one of the characters in his name from Yoshiyasu, adopted the name of Yasuuji. However, after Yoshiyasu was killed by Yoshiaki, he received a character in his name from his father and adopted the name of Mitsuuji.
After becoming a hostage of the Mogami, he developed a relationship with Toyotomi Hideyori. At the Battle of Sekigahara, he served as the commander-in-chief of forces pursuing the Uesugi army. In 1614, just before the Winter Campaign of the Siege of Ōsaka, he was suspected of colluding with those on the side of the Toyotomi and incurred an attack by his older brother, Iechika, at Shimizu Castle. Yoshichika, together with his eldest son and designated heir, Shimizu Yoshitsugu, was forced to take his own life.
While Yoshichika became a hostage of the Toyotomi family, Iechika served the Tokugawa family so the siblings did not enjoy good relations. Even after Yoshiyasu was murdered, documents continued to be issued within Yoshichika’s territory under a seal in the name of “Yoshiyasu” that had earlier been given to Yoshichika. There is a theory that Yoshichika supported Yoshiyasu and harbored ill-will toward Iechika. Known as a location for transport on the Mogami River, the area of Shimizu was the subject of fighting between the Mogami and Daihōji clans for many years. To control the rights to transport on the Mogami River, Iechika may have aimed to place the area of Shimizu under his direct jurisdiction. It is surmised that these factors together led Iechika to attack Yoshichika.